Police are investigating whether cash given to animal rights' protesters is funding illegal activities targeting Oxford University's research laboratory.

Thames Valley Police said they could use new legislation to seize assets behind criminal campaigns if it could prove there was illegal activity.

Protest group Speak, which has led demonstrations against the £18m laboratory, is one of the organisations whose finances are being investigated, a spokesman for the force said yesterday.

But Speak spokesman Mel Broughton insisted it had nothing to hide.

The police spokesman said: "We are investigating the finances of these groups, including Speak, but this is at a very early stage.

"We are doing background work, not preparing to seize funds at this stage. That may or may not be appropriate or necessary.

"If money is going to be seized, then there would be no obligation to warn Speak or any other group it could happen at any time but there would be a formal process which would involve the courts."

The force plans to seize any money it finds being used to fund criminal activity, under last year's Serious and Organised Crime Act, and the Proceeds of Crime Act.

Mr Broughton said: "The police can come and have a look at our books and bank statements any time. Speak are not linked to the Animal Liberation Front, we are not funded by the ALF, and we are a completely legal organisation.

"I think this is part of a politically-driven, orchestrated effort to demonise Speak, and that is quite worrying in a so-called democratic society.

"But this kind of thing just galvanises our supporters and makes them even more determined to protest."

On Monday, Oxford University is seeking to extend a High Court injunction banning the use of megaphones at the laboratory site.

Last month, the university won an interim order banning campaigners from using megaphones, klaxons, sirens and whistles or taking photographs outside the building site in South Parks Road. It wants a judge to extend the interim order to anywhere in the city.

The ALF has claimed responsibility for damaging an Oxford architects firm earlier this year. It also set fire to Hertford College boathouse last year.