Australian Prime Minister Scott Morrison and Labor leader Anthony Albanese have clashed in a fiery debate over China's new security agreement with the Solomon Islands, which Labor has called "the worst failure of Australian foreign policy in the Pacific since the end of World War II".

In the first leaders' debate ahead of the 2022 federal election, Morrison said China had been increasing its interference in the region for years and suggested Labor's criticism of his government showed it was siding with China.

"Somehow they're saying it's Australia's fault," Morrison said. "What I don't understand is, when something of this significance takes place, why would you take China's side?"

With a few audible groans among the group of undecided voters in the audience, Albanese accused Morrison of an "outrageous slur" and said "national security issues shouldn't be subjected to that kind of slur".

The Labor leader's argument was that the government had been complacent. He criticised Morrison for sending Zed Seselja, Minister for International Development and the Pacific, to the Solomon Islands to convince them to nix the pact, instead of Foreign Minister Marise Payne.

He also cited comments from former Liberal foreign minister Julie Bishop, who told reporters she believed Payne "should be on the next plane to the Solomon Islands" to determine what exactly the pact entails and how it impacts "Australia's security interests".

Chinese Premier Li Keqiang and Solomon Islands Prime Minister Manasseh Sogavare at a welcome ceremony at the Great Hall of the People in Beijing. Photo / AP

Solomon Islands Prime Minister Manasseh Sogavare confirmed on Wednesday that his government had signed the pact with China, but told lawmakers it would not "undermine the peace and harmony of our region" as has been feared by the opposition and other countries including the United States, Australia and New Zealand.

The security agreement allows China to send police and military personnel to the Solomon Islands "to assist in maintaining social order," while also opening the door for Chinese warships to stop in port there for "logistical replenishment" — giving rise to worries of a possible Chinese naval base in the Pacific.

But in his address to Parliament, Sogavare defended the security agreement as being directed entirely to "our internal security situation". He said it complemented a 2017 security arrangement with Australia, under which Australian police peacekeepers have been in the capital, Honiara, since riots in November.

"I ask all our neighbours, friends and partners to respect the sovereign interest of Solomon Islands on the assurance that the decision will not adversely impact or undermine the peace and harmony of our region," he told Parliament.

Solomon Islands Prime Minister Manasseh Sogavare, left, and Chinese Premier Li Keqiang attend a signing ceremony at the Great Hall of the People in Beijing. Photo / AP

A draft of the agreement leaked online last month, and China's Foreign Ministry announced Tuesday that it had been signed "the other day". Sogavare was equally vague, telling lawmakers that it had been signed "a few days ago".

Australia had urged the Solomon Islands not to sign the pact and New Zealand Foreign Minister Nanaia Mahuta said the agreement is unwelcome and unnecessary. Two top American officials — Kurt Campbell, the National Security Council Indo-Pacific coordinator, and Daniel Kritenbrink, the assistant secretary of state for East Asian and Pacific affairs — are also set to visit the country this week for talks.

Sogavare has said his government would not let China build a military base, and China has denied seeking a military foothold in the South Pacific.

After China announced the agreement had been signed, Seselja and Payne said in a joint statement that they were "deeply disappointed".

"Our consistently stated view, including from the perspective of Australia's national interests, remains that the Pacific family is best placed to meet the security needs of the region.

"We are concerned about the lack of transparency with which this agreement has been developed, noting its potential to undermine stability in our region."

New Zealand Prime Minister Jacinda Ardern and Australian Foreign Minister Marise Payne at the MFAT offices in Auckland. Photo / Jason Oxenham

They added that they welcomed statements from Sogavare that the "Solomon Islands will never be used for military bases or other military institutions of foreign powers".

Earlier this week, US State Department spokesman Ned Price said the agreement could destabilise the Solomon Islands and would set a concerning precedent for the wider Pacific region.

"Despite the Solomon Islands government's comments, the broad nature of the security agreement leaves open the door for the deployment of PRC [People's Republic of China] military forces to the Solomon Islands."

Micronesia and other Pacific Island nations have also expressed concerns about the deal, as has the Solomon Islands' main opposition party.

In his address, Sogavare defended the pact, saying it would strengthen the country's police and help them deal with future instability, and that it was "based on mutual respect for sovereignty and in compliance with domestic and international law".

"Let me assure the people of Solomon Islands that we entered into an arrangement with China with our eyes wide open, guided by our national interests."

Additional reporting: AP, news.com.au