A home in Middletown, Skipton, was raided early today as part of an international animal rights extremism operation.
The crackdown is being led by Hampshire police and so far 30 people have been arrested.
Officers have raided premises in Yorkshire, Berkshire, Hampshire, Surrey, Sussex, Kent, Greater London, Merseyside, Worcestershire, Lancashire, Northumbria, Belgium and the Netherlands.
The people arrested are all suspected of being involved in criminal activity associated with animal rights extremism.
All have been taken to undisclosed police stations across the country and will be interviewed throughout the day.
The operation has been led by forces from the south east region and supported by a number of other UK police forces and European law enforcement agencies.