Russian President Vladimir Putin said today NZT that the gunmen who killed 139 people at a suburban Moscow concert hall are “radical Islamists”, but he repeated his accusation that Ukraine could have played a role despite its strong denials.

Speaking in a meeting with government officials, Putin said the killings were carried out by extremists “whose ideology the Islamic world has been fighting for centuries”.

Putin, who declared over the weekend that the four attackers were arrested while trying to escape to Ukraine, said investigators haven’t determined who ordered the attack, but that it was necessary to find out “why the terrorists after committing their crime tried to flee to Ukraine and who was waiting for them there”.

The Afghanistan affiliate of Isis (Islamic State) claimed it carried out the attack, and United States intelligence said it had information confirming the group was responsible. French President Emmanuel Macron also said France has intelligence pointing to “an Isis entity” as responsible for the attack.

“We are seeing that the US , through various channels, is trying to convince its satellites and other countries of the world that, according to their intelligence, there is allegedly no Kyiv trace in the Moscow terror attack — that the bloody terrorist act was committed by followers of Islam, members of [Isis],” Putin said during a meeting with top law enforcement officials.

He added that “those who support the Kyiv regime don’t want to be accomplices in terror and sponsors of terrorism, but many questions remain”.

Putin went on to declare that Ukraine has sought to deflect attention from its battlefield setbacks by waging cross-border attacks on various Russian regions, adding that “bloody intimidation acts like the Moscow terror attack look like a logical part of this chain”.

An Orthodox priest conducts a service at a makeshift memorial in front of the Crocus City Hall in the outskirts of Moscow, Russia. Photo / AP

The attack on Saturday NZT at the Crocus City Hall music venue on the western outskirts of Moscow left 139 people dead and more than 180 injured, proving to be the deadliest in Russia in years. About 100 people remained hospitalised, officials said.

Putin warned that more attacks could follow, alleging possible Western involvement. He didn’t mention the warning about an imminent terror attacks that the US confidentially shared with Moscow two weeks before the raid or the public.

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Three days before the attack, Putin denounced the March 7 US Embassy notice urging Americans to avoid crowds in Moscow, including concerts, as an attempt to frighten Russians and “blackmail” the Kremlin ahead of the presidential election.

The four suspected attackers, all of them nationals of Tajikistan, were remanded by a Moscow court yesterday with carrying out the attack and ordered to remain in custody pending the official probe.

Russian media reported that the four were tortured while being interrogated, and they showed signs of being severely beaten during their court appearance.

Russian officials said all four pleaded guilty to the charges, which carry a life punishment, but their condition raised questions about whether their statements might have been coerced.

Russian authorities reported that seven other suspects have been detained, and three of them were remanded by the court today on charges of being involved in the attack.

As they mowed down concertgoers with gunfire, the attackers set fire to the vast concert hall, and the resulting blaze caused the roof to collapse.

The search operation will continue until at least tomorrow, officials said. A Russian Orthodox priest conducted a service at the site, blessing a makeshift memorial with incense.

A police officer stands guard holding an anti-drone rifle in the outskirts of Moscow, Russia. Photo / AP

Russian officials and lawmakers have urged a severe punishment for all those involved in the attack, and some called for the restoration of capital punishment outlawed since 1997.

During yesterday’s court hearing, three of the suspects showed signs of heavy bruising, including swollen faces. One of them was in a wheelchair in a hospital gown, accompanied by medical personnel, and sat with his eyes closed throughout. He appeared to have multiple cuts.

Another had a plastic bag still hanging over his neck and a third man had a heavily bandaged ear. Russian media reported at the weekend that one suspect had his ear cut off during interrogation. The Associated Press couldn’t verify the report or videos purporting to show this.

Dmitry Medvedev, who was Russia’s president from 2008-12 and now serves as deputy head of Security Council chaired by Putin, urged to “kill everyone involved. Everyone. Those who paid, those who sympathised, those who helped. Kill them all.”

Margarita Simonyan, head of the state-funded television channel RT, argued that even the death penalty — currently banned in Russia — would be “too easy” a punishment.

Instead, she said they should face “lifelong hard labour somewhere underground, living there too, without the opportunity to ever see light, on bread and water, with a ban on conversations and with a not very humane escort”.

Russian human rights advocates condemned the violence against the men.

A screen grab from a video shows smoke rises from fire as ambulances, personnel arrive at Crocus City Hall concert venue near Moscow. Photo / AP

Team Against Torture, a prominent group that advocates against police brutality, said in a statement that the culprits must face stern punishment, but “savagery should not be the answer to savagery”.

It said the value of any testimony obtained by torture was “critically low”, and “if the Government allows for torture of terrorism suspects, it may allow unlawful violence toward other citizens, too”.

Net Freedoms, another Russian group that focuses on freedom of speech cases, said Medvedev’s remarks, as well as Putin’s recent call on security services to “punish traitors without a statute of limitation no matter where they are”, made against the backdrop of “demonstrative torture of the detained ... effectively authorise extrajudicial killings and give instructions to security forces on how to treat enemies.

“We’re seeing the possible beginning of the new Great Terror,” Net Freedoms said, referring to mass repressions by Soviet dictator Josef Stalin. The group foresees more police brutality against suspects in terrorist-related cases and a spike in violent crimes against migrants.

Abuse of suspects by law enforcement and security services isn’t new, said Sergei Davidis of the Memorial human rights group.

“We know about torture of Ukrainian prisoners of war, we know about mass torture of those charged with terrorism, high treason and other crimes, especially those investigated by the Federal Security Service. Here, it was for the first time made public,” Davidis said.

Parading beaten suspects could reflect a desire by authorities to show a muscular response to try to defuse any criticism of their inability to prevent the attack, he said.

The concert hall attack was a major embarrassment for Putin and came less than a week after he cemented his grip on Russia for another six years in a vote that followed the harshest crackdown on dissent since Soviet times.

Many on Russian social media questioned how authorities and their vast security apparatus that actively surveils, pressures and prosecutes critics failed to prevent the attack despite the US warning.

Citing the treatment of the suspects, Davidis told AP that “we can suppose it was deliberately made public in order to show the severity of response of the state”.

“People are not satisfied with this situation when such a huge number of law enforcement officers didn’t manage to prevent such an attack, and they demonstrate the severe reaction in order to stop these accusations against them,” he said.

The fact that the security forces did not conceal their methods was “a bad sign”.

Isis, which fought Russian forces that intervened in the Syrian civil war, has long targeted the country. In a statement posted by the group’s Aamaq news agency, the Isis Afghanistan affiliate said it carried out an attack in Krasnogorsk, the suburb of Moscow where the concert hall is located.

In October 2015, a bomb planted by Isis downed a Russian passenger plane over Sinai, killing all 224 people aboard, most of them Russian tourists returning from Egypt.

The group, which operates mainly in Syria and Iraq but also in Afghanistan and Africa, has claimed responsibility for several attacks in Russia’s volatile Caucasus and other regions in past years. It recruited fighters from Russia and other parts of the former Soviet Union.