THE boss of a North Yorkshire power station at the centre of a massive environmental protest has hit back at eco-warriors who tried to shut down the plant.

Dorothy Thompson, chief executive of Drax Power Station, said the plant was more efficient than any other coal-fired station in Britain, and claimed the campaigners had targeted them because of their size rather than their record.

The message came as the dust settled on Thursday's day of direct action, which saw hundreds of demonstrators from the ten day Camp For Climate Action descend on Drax.

A large police operation saw officers from 11 forces drafted in to help oversee the protests and protect the power plant.

Yesterday, another activist was arrested for possessing an offensive weapon, taking the total number of arrests to 39.

Ms Thompson said: "We understand the seriousness of climate change and we are working hard on ways to reduce our emissions of carbon dioxide. The quickest way for us to achieve significant reductions is to increase the amount of energy crops and other biomass materials that we burn, and we are working closely with Government to ensure that policy changes are delivered to make this happen.

"We are already the most efficient coal-fired power station in the country, which means that we emit less CO2 for each unit of electricity that we produce. But, because we are nearly twice as big as the next largest power station, that made us a target.

"During the day of protest, our concern was for safety and security of electricity supply. We greatly regret the disruption caused to our neighbours and we very much appreciate the help and assistance provided by the police."

A North Yorkshire Police spokesman said the number of people at the camp, on Barlow Common between Selby and Drax, was beginning to reduce, but said Operation Harmony would remain in place until the last of the demonstrators had left.

The spokesman said: "We are still doing an assessment to see how many are still on the site.

"The operation will continue right as long as necessary - as long as there is a presence there from the camp.

"We do not know what will happen but we are prepared and we have the resources to deal with anything."

About 600 protestors took part in the day of action, fewer than the 2,000 predicted, but the campaigners declared the day a success.

Group spokesperson Sophie Stevens said: "Everyone is really delighted and really excited. This was really about having a big spectacular bang for the beginning of a new social movement and it's about direct action - not just for now but for the future.

Of the 39 arrests, 16 were for aggravated trespass. Two women have been charged and will appear before York magistrates on Wednesday, while the rest have been bailed pending further inquiries.

There were 13 people arrested for criminal damage, all of whom have been released pending further inquiries.

Other arrests were for possessing offensive weapons, public order offences, or causing obstruction to the police.

Two farmers were also arrested after apparently trying to force their way through crowds in their tractors.

One was dragged from his vehicle by police officers and they were both arrested to prevent a breach of the peace.

A police spokesman said the farmers were not part of the protest, but felt the needed to get past to get to their farms.