Animal Rising claimed 25 supporters had made it onto the track and posted a video on their Twitter feed showing at least four activists breaking through the fence around the racecourse at Ayr, with some making it onto the track.

None of them successfully attached themselves to jumps and gates and they were not able to cancel or delay the big race, which was won by pre-race favourite Kitty's Light.

A statement by the group said: "This afternoon eight-year-old Oscar Elite died on the very same track [as the Scottish Grand National]. We take action today with them in our hearts. A horse dies every other day in racing in the UK.

"We are here to protect horses by saying NO to this barbaric 'sport.' There are plenty of other things we can have fun doing on a Saturday afternoon that don't involve watching animals come to harm."

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Police Scotland tweeted they were "responding to a protest which is ongoing at Ayr Racecourse this afternoon. A significant operation is under way to safely remove those involved.

"A number of arrests have been made and an increased police presence remains at the scene."

Ayr's managing director David Brown praised the swift action of the police and security teams on course.

"The race went off to time, there was no notable delay and the professionalism of the team up here in Scotland was a credit to them, they dealt with it in a very efficient manner," he said.

"What a great race it was and a great story, for Christian Williams to win it for the second year in a row with Kitty's Light, after he finished second last year. I think for me this is Scotland's showpiece race and it all ran to time."

Last Saturday, more than 110 people were arrested for criminal damage and public nuisance offences after they tried to stop the Grand National at Aintree.

Nine protesters made it onto the race track and tried to attach themselves to fences. The race was delayed by 15 minutes by their actions.