Police swooped on TV writer Carla Lane's animal sanctuary this morning in a string of Sussex arrests over an attack on a pharmaceutical firm's boss.

Three men were arrested in the county, one of them at a cottage on Ms Lane's land at Horsted Keynes, near East Grinstead, the well-known animal rights campaigner said.

Ms Lane said more than 60 officers began a fingertip search of her premises and the neighbouring cottage for clues to the attack, including firearms and maps.

A 34-year-old man, whom Ms Lane declined to name, was among those detained by officers investigating an assault on Brian Cass, head of Huntingdon Life Sciences in Cambridgeshire.

Mr Cass was attacked as he arrived at his home in St Ives, Cambs, on February 22.

Ms Lane said the man was arrested at a cottage on her land.

She said: "The man does not work for me and does not live here but does visit a friend who works at the sanctuary.

"The whole thing is a great shock to us."

She added: "We are co-operating fully with the police. There are 60 or 70 officers here, some wearing white coats. They came and said they wanted to search the sanctuary.

"They are searching the cottage and the sanctuary. They said they were searching for firearms and maps. I have just let them do it. Most people are being guarded. I am the only one who has not been assigned a guard.

"It looks like the scene of a Hollywood blockbuster, but I am not taking this lightly. It is actually quite frightening."

Huntingdon Life Sciences has been the focus of a series of protests because of its use of animals for drug testing.

A police spokeswoman said three men were being returned to Cambridgeshire from Sussex to be interviewed by detectives.

The two other suspects, aged 31 and 34, were arrested in Hastings early this morning.

Mr Cass, who is in his early 50s, suffered head injuries in the attack.

The arrested men will also be questioned about an attack on a man who went to Mr Cass's aid and about alleged possession of a prohibited firearm.