A 33-year-old woman has been arrested in connection with potential co-ordinated disruption activities at Saturday’s Grand National at Aintree.
The woman from the London area was arrested in Greater Manchester on Saturday morning on suspicion of conspiracy to cause public nuisance.
Merseyside Police said they had planned for the possibility of protests.
Around 30 animal rights protesters had gathered outside the racecourse on Saturday morning.
The police had previously said they would deal “robustly” with any disruption after animal rights activists threatened to sabotage the race.
“Merseyside Police has been working with The Jockey Club and other partners to keep people safe during the Grand National Festival,” they said in a new statement.
“We are aware of some people planning to protest at the event. This has been factored into our plans. We respect the right to peaceful protest and expression of views, but criminal behaviour and disorder will not be tolerated and will be dealt with robustly.”
A field of 39 runners is set to contest the 175th running of the famous race at 17:15 BST.
Climate and animal rights group Animal Rising said up to 300 activists would attend the venue on Saturday morning and aim to prevent the race from starting by entering the track.
Aintree Racecourse warned their actions could “endanger the horses they purport to protect, as well as jockeys, officials and themselves”.