Chimney climbers halt EDF gas plant in England

* West Burton coal plant unaffected

* Unit 2 at gas plant to start at end of year, others in 2013

* Police arrest five women on suspicion of aggravated trespass

By Karolin Schaps

LONDON, Oct 29 (Reuters) - EDF Energy interrupted commissioning work at the new 1,300-megawatt (MW) West Burton gas-fired power plant in England on Monday after environmental campaigners climbed chimneys in protest against use of fossil fuels.

Police arrested five women on suspicion of aggravated trespass at the plant after more than 20 protesters entered the site in the early hours of Monday, climbed two chimneys and chained themselves to the structures.

"They have enough supplies with them to last at least a week and say they're in it for the long haul," the No Dash For Gas campaign group, which wants the government to halt investments in new fossil fuel plants and support renewable energy, said in a statement.

"Electricity generation has been halted (at unit 2) because of safety reasons," a spokeswoman for EDF Energy said. Another spokesman added that production at the adjacent West Burton coal-fired power plant was unaffected.

The three units at the new power plant are still in commissioning stage and unit 2 is expected to start fully operating by the end of the year, while units 1 and 3 will start in 2013, EDF Energy said.

Unit 2 at the power plant had been producing electricity as part of start-up work since mid-September, but output dropped to zero on Monday, National Grid data showed.

Units 1 and 3 had not been producing any electricity, the same data showed.

Police in Nottinghamshire, in England's East Midlands, were monitoring the protests on Monday and began negotiations with the protestors to end their demonstration.

Assistant Chief Constable Paul Broadbent, leading the police operation, warned that a one-week long protest could cost Nottinghamshire taxpayers more than 200,000 pounds (${esc.dollar}320,500).

"Those involved in planning and participating in this illegal action can expect to be arrested," he said.

The West Burton plant has three exhaust stacks, also called chimneys, and at 1250 GMT around 10 protesters were atop one of the chimneys and 6 protesters on another, EDF Energy said.

Britain's Energy and Climate Change Secretary said earlier this month he expected 20 gigawatts (GW) of new gas-fired power capacity to be built in Britain by 2030.

The government is in the process of reforming the UK's energy market, aiming to reward low-carbon production from sources such as wind farms or nuclear power stations but ensure flexible fossil-fuel plants are on standby to fill supply gaps.(${esc.dollar}1 = 0.6241 British pounds)