The six, who include environment journalist George Monbiot, were charged on Wednesday by North Wales Police and will appear at Mold magistrates' court on 20 November.

A policeman places a protester under arrest

It is expected the protesters will plead not guilty to the criminal damage of the fodder maize crop, which is being grown by Flintshire farmer John Cottle.

The six are understood to be prepared to claim in court they acted in the public interest and continue their argument that Wales should be GM-free.

One person was injured in the protest last July at Sealand, as an estimated 40 protesters broke into a field and allegedly began pulling up the crop.

A large police presence and force helicopter had supervised the protest.

Mr Cottle said at the time of the incident that he was disappointed the protesters had broken into his field.

George Monbiot: Charged with criminal damage

Earlier in the day, protesters had held an all-day rally calling for an end to Wales's only GM trial.

Mr Cottle refused a call from Rural Affairs Minister Carwyn Jones to abandon the trials on the English border.

In May, separate trials at Castle Cenlas Farm in Pembrokeshire were abandoned when farmer and former MP Tony Marlow accused the government of sending misleading messages over genetically-modified food.

At Sealand, local organic farmers are concerned about cross-contamination but Mr Cottle remains convinced about the benefits of the trials.