A GM foods protester was fined more than £400 yesterday for damaging a metal fence that collapsed under his weight as he tried to destroy a field full of genetically modified potatoes.

Activist Martin Shaw, from Campbell Road, Oxford, failed in his bid to rip up the crop of spuds and was instead found guilty of criminal damage to the 6ft mesh fence which buckled under his weight as he tried to scale it.

The field of potatoes, which is being developed to be blight resistant by German-based company BASF in Cambridgeshire, was destroyed just days later by other activists.

Shaw, 43, has been arrested on five previous occasions for protesting against GM foods. He said he would appeal against the conviction.

His only regret, he added, was that he failed to uproot the potatoes.

Speaking after the hearing, he said: "I was committing a 'crime' to prevent a greater crime... to prevent genetic pollution.

"I just regret not having pulled up the plants. I believe the vast majority of the British public would prefer Britain to be and remain GM-free.

"Every day, millions of people are making decisions about GM crops versus organic crops and they are voting with their feet."

And he defended the direct action protests which left him owing £100 in compensation to the multinational chemicals corporation.

"This was the last test site in the whole country. Ten years ago there were hundreds of test sites in this country.

"Some times it (direct action) is the only way."

Shaw was arrested by police protecting the 40-metre square field in July this year during an anti-GM foods protest.

He evaded the police officers guarding the site during the protest but was arrested when he fell to the ground as the mesh fence collapsed.

He admitted he planned to destroy the crop but denied one charge of criminal damage to the fence, saying he believed the metal railings would be able to hold his weight.

Magistrates in Cambridge disagreed and ruled he was reckless as to whether damage would be caused to the fence panel.

Shaw, was fined £125, ordered to pay compensation of £100 as well as £200 in costs.

Just days after Shaw's arrest, campaigners scaled security fences in the early hours to get into the field between Girton and Histon, and pulled up the crop.

BASF had stepped up security at the site following threats to the trial and obtained a High Court injunction banning people from entering the field.