Merseyside Police held nine people who had managed to enter the track.

They later said there had been a total of 118 arrests for both "criminal damage and public nuisance offences".

That includes arrests before the race on Saturday and in relation to a protest that blocked the M57.

The race started 14 minutes late after its scheduled start time of 17:15 BST.

The 175th edition was won by Corach Rambler, ridden by Derek Fox.

One horse, Hill Sixteen, died after falling at the first fence, meaning there have been three horse deaths at the 2023 meeting overall.

"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."

Television pictures appeared to show some protesters making it on to the track and trying to attach themselves to a fence, before being removed by police.

Dozens of others attempted to climb over or glue themselves to security fencing around the track but were led away, with police also confiscating ladders.

Climate and animal rights group Animal Rising, who earlier demonstrated outside Aintree, claimed on social media their supporters entered the track to delay the race.

Traffic was also blocked by protesters on the M57 motorway shortly before activists entered the track at Aintree.

North West Motorway Police said there was "a number of people sat on the M57" at junction two northbound, and traffic was stopped in both directions. The road fully reopened shortly after 20:00.

Merseyside Police Assistant Chief Constable Paul White said: "Today, as you've seen, there's been a significant protest in relation to the running of the Grand National.

"This began earlier this morning. There's been a number of protests outside and then that resulted earlier on today at about 5pm with numerous people trying to incur onto the course, which we, in partnership with the event organisers, and members of the public as well, have managed in the main to stop and and ultimately the event took place - albeit with a slight delay."

Mr White said it required "significant resource" to cover the perimeter of Aintree, with protesters attempting to access the course from a number of points around the track.

He said police had a "proportionate" plan in place and were able to stop "the vast majority" from entering the course, and those who did were removed "swiftly".

Protesters were still being led away by police outside the security fencing while the race was going on

Mr White added: "We've had to uplift our resources significantly. Clearly we were very much aware there was a planned protest today.

"We always have a proportionate policing plan in place to manage the event and support event organisers, but because of the additional information and intelligence regarding protests we had to increase resources significantly for today."

After the delay was announced on the racecourse public address system, the 39 participating horses were taken back to the pre-parade ring.

The jockeys were asked to re-mount their rides six minutes after the scheduled start time, with the race starting eight minutes later.

Dickon White, who runs the track as North West regional director for the Jockey Club, said the delay was caused by the "reckless actions of a small number of individuals".

Merseyside Police thanked the public for their "patience" while they dealt with the protests.

The police had previously said they would deal "robustly" with any disruption after animal rights activists threatened to sabotage the race.

Police confiscated ladders from protesters attempting to climb over security fencing

Aintree Racecourse warned that the actions of protestors could "endanger the horses they purport to protect, as well as jockeys, officials and themselves".

Speaking before protesters entered the track, Animal Rising spokesperson Nathan McGovern said: "Police are wasting time chasing protesters rather than addressing the climate and ecological emergency, and our broken relationship to animals.

"We remain undeterred, and we will peacefully continue our actions to stop harm coming to animals at Aintree.

"Today marks the first of many actions that will really take place this summer to push this conversation to the top of the agenda."

Animal Rising posted photos on social media appearing to show supporters slow-marching around Aintree on Saturday afternoon.

The total of 118 arrests includes three people who were earlier held in connection with potential co-ordinated disruption activities.

A 25-year-old woman from London and a man were arrested outside Aintree on suspicion of conspiracy to cause public nuisance.

A 33-year-old woman from the London area was arrested in Greater Manchester on suspicion of the same offence.

Animal Rising claimed one of those arrested earlier on Saturday was one of its members, 25-year-old Claudia Penna Rojas.

As well as the death of Hill Sixteen, Dark Raven was put down earlier on Saturday following a fall during the Turners Mersey Novices' Hurdle at Aintree, while Envoye Special suffered a fatal injury in the Foxhunters' Chase on Thursday.

Two other horses in the Grand National - Recite A Prayer and Cape Gentleman - were treated on course and taken away by horse ambulance for further assessment.

There have been five fatalities from 395 runners in the 10 Grand Nationals raced since safety changes were introduced in 2012.

Bookmakers expected more than £150m to be wagered on the National, which takes place over 30 fences and four and a quarter miles.

A heavy police presence was seen outside Aintree on Saturday