As controversy increases over trials of genetically-modified (GM) crops, the government's own wildlife watchdog has told BBC News Online the trials ought to go ahead.

The advisory body, English Nature, has expressed reservations about GM crops in the past.

Last year it wrote to the prime minister warning him that crops modified to resist herbicides should not be grown commercially until research had been completed.

'Devastating' blow

It urged a three-year ban to allow time for the research to be carried out.

Opponents of GM crops said English Nature's letter was "devastating" for the biotechnology companies.

And in March two senior officials told a Parliamentary committee that, while English Nature did not oppose GM crops in principle, it believed they could threaten wildlife.

Last month Greenpeace claimed to have undermined the entire GM test process after its supporters allegedly destroyed a field of modified maize in Norfolk.

Inviting targets

The government this week announced the locations of four farm-scale trials of GM oilseed rape, to begin this autumn.

There are fears that the trials could again be the target of action by protesters.

But an English Nature spokeswoman told BBC News Online: "They should go ahead.

An anti-GM picnic draws the crowds

"We are not happy with the fact that trial crops are being destroyed, and we do not condone their destruction.

"All we can do is advise the government on how scientifically it can assess the safety of these crops.

"We asked for the trials, we support them, and we are on the steering group set up to oversee the research."

Dr Doug Parr, campaigns director for Greenpeace, defended the campaigners' tactics.

'When democracy fails'

He told BBC News Online: "Farm-scale trials are backdoor commercialisation of GM crops that nobody wants, and they threaten the future of organic agriculture".

"The government is misusing science to provide bogus legitimacy for them.