The Greenpeace environmental protest at Didcot Power Station ended yesterday, after campaigners were handed a court injunction ordering them to leave.

But the demonstration, which lasted nearly 36 hours, has cost the station's owner npower more than £500,000.

At 3.30pm, police said the protest had ended and 25 people had been arrested on suspicion of aggravated trespass and criminal damage.

The demonstration began at 5.30am on Thursday when two groups of Greenpeace campaigners entered the site.

One team climbed to the top of the station's 650ft chimney stack via an internal staircase.

Later, using abseiling equipment, they wrote 'Blair's Legacy' down the side of the stack in large letters.

The second group chained themselves to a coal conveyor belt, 60ft above the ground, after switching off the machinery.

The demonstration forced npower to halve output at the coal-fired Didcot A power station on Thursday.

By yesterday morning, engineers had re-established a coal supply to the boilers, but the plant continued to run below capacity. Npower said last night that it would take 24 to 48 hours to resume normal output.

Throughout the protest, a team of specialist police negotiators tried to persuade the campaigners to end their demonstration.

However, it was a High Court injunction, sought by npower, that finally ended the protest. Shortly before 2pm, the injunction notice, ordering the Greenpeace members to leave the site, was pinned to the gates of the power station.

Copies were also delivered to Greenpeace's headquarters in London.

By 2.30pm, a Greenpeace spokesman confirmed the injunction would be obeyed.

At 3.30pm, Supt Jill Simpson, police commander for south Oxfordshire, said all protesters had come down from the chimney and the coal conveyor.

She added: "They have come down safely and that's the best outcome for everybody.

"This was potentially a very dangerous situation. Everyone has the right to protest peacefully, but we also have a duty to ensure people can go about their lawful business. Together with npower, we managed to ensure that the power station continued to function throughout the protest."

She confirmed it had been a sizeable police operation, but could not put a figure on the cost.

She admitted the protest had affected the force's ability to police the district, but she insisted it had not affected responses to 999 calls and other emergencies.

Greenpeace spokesman Laura Yates, who was stationed outside the plant's perimeter fence, said the protest was justified.

She said: "Since Greenpeace have been here, we believe we have halved the CO2 emissions from the site by stopping coal getting in and reducing power generation.

"I think peaceful direct action is justifiable when you have tried many alternatives that have not succeeded and you can achieve a more concrete result from this."