The UK’s Grand National, one of the world’s most famous horse races, was delayed on Sunday after animal rights activists scaled fences around the perimeter of Aintree racecourse and got on to the track.

A total of 118 people were arrested on suspicion of criminal damage and public nuisance offences in a bid to disrupt the race, Merseyside Police said.

It comes as a total of three horses have now died during the three-day event.

Many activists from an estimated group of 300 climbed the high fences around the racecourse just outside Liverpool and got on to the track a few minutes before the race was scheduled to start. Some affixed themselves to the race fences using glue and lock-on devices, according to the Animal Rising organisation, before being taken away by police and security officials.

Police and security officials were seen stopping other activists by shaking the perimeter fences to prevent them from being climbed. Local residents were seen helping security keep activists away from the course.

Protesters are detained by police during day three of the Grand National at Aintree Racecourse in Liverpool. Photo / Getty Images

The race was delayed as a result and the 39 competing horses were kept in the parade ring. It was originally scheduled to begin at 5.15 pm local time (4.15 am NZT) and ended up starting around 15 minutes later.

The day started with three people arrested in connection with a plan by the activists to disrupt the race. All three were arrested on “suspicion of conspiracy to cause public nuisance,” police said. Their names were not disclosed.

“We respect the right to peaceful protest and expression of views,” Merseyside Police said, “but criminal behaviour and disorder will not be tolerated and will be dealt with robustly.”

According to Sky Sports News a third racehorse, Hill Sixteen, suffered a fatal fall at the first fence after two other animals had also died.

Dark Raven died after racing earlier on Sunday while Envoye Special died on Friday.

Animal Rising had called on protesters to gather outside the racecourse to demand an end to “animal cruelty for entertainment.” The group tweeted a video that it said shows one of its spokespeople being arrested at the protest.

Police said they have been working with race organisers ahead of and during the Grand National Festival, which started Friday.

Animal Rising activist Alex Lockwood this week told British radio station talkSPORT that they planned to disrupt the Grand National, arguing that standing outside and handing out fliers “never stopped anything.”

“This horrific ‘sport’ continues to take lives right in front of our eyes. It’s time to BAN this horrific industry,” Animal Rising wrote.

The Grand National is among the biggest occasions on the British sporting calendar and is regarded as one of the most dangerous horse races in the world because of the size of the fences.

Changes were made in 2012 to make the course safer, including softening some of the fences, after two horses died in the Grand National that year and in 2011.

There have been four fatalities from 356 runners in the nine Grand Nationals since. Four horses died at the Aintree festival last year, including two who were injured in the Grand National. - AP