The race started at 5.27pm (instead of 5.15pm) after around 15 Animal Rising demonstrators were reported to have been on the track, with at least two affixing themselves to a jump using glue and lock-on devices, according to the climate and animal rights group.

The protestors breached security fences to get onto the track, before some were arrested.

"Just after 5pm, a large number of protesters attempted to gain entry on to the course," Merseyside Police said.

"The majority were prevented from breaching the boundary fencing, but the nine individuals who managed to enter the course were later arrested by officers."

Student Sarah McCaffrey, who was one of those disrupting the track said: "I know everyone coming to Aintree to view the races today would say they love the horses; however, the suffering experienced by them should shock us all.

"That's why I've decided to put my body between those horses and death on the racecourse, rather than gamble with their lives."

When the race got under way it was Corach Rambler, ridden by Derek Fox and trained by Lucinda Russell that stormed to victory to win the race, which lasted around 10 minutes.

Animal Rising said that several horses fell during the race, which is what their protest had been trying to stop.

"Today marks not the end, but the beginning, of the summer of Animal Rising. We will be defending animals and nature and creating an unignorable national conversation about our relationship to animals and the natural world," spokesperson Orla Coghlan said.

Read more:
Animal Rising protesters say they'll try to stop Grand National
Opinion - 'I loved the Grand National until I saw what I saw'

Earlier, the animal rights group announced plans to prevent the steeplechase from starting, with up to 300 activists planning to scale fences and enter the track.

It said: "We will be slow marching around the perimeter and at some point we may peacefully try to make our way towards the track, again to prevent this race from happening because we know horses are being harmed."

Ahead of the Grand National race, three people were arrested on suspicion of conspiracy to cause a public nuisance, including 25-year-old spokesperson Claudia Penna Rojas.

A man and a 33-year-old woman were detained in Greater Manchester on suspicion of the same offence.

Some racegoers did not seem to notice the delay caused by the presence of protesters.

Alice Pocock, 29, from Newbury, Berkshire, said: "All my friends messaged asking if we'd seen the protesters but we didn't notice, I just wondered why the race was delayed.

"Every horse here is born and bred to race. I think the protesters are putting themselves at harm and they don't understand the racing industry."