A group of climate protesters threatened to disrupt an airport after setting up a barricade on the runway.

Plane Stupid said seven people had broken through the perimeter fence at Aberdeen Airport and placed themselves inside a wire "fortress" on the tarmac. Several other protesters had climbed on to the roof of the terminal building, it added.

The group said the activists invaded the site shortly after 2am and that they were hoping to prevent the airport from reopening later on Tuesday morning.

A spokesman for airport operator BAA said: "Seven people appear to have cut a hole in the security perimeter and are now on the runway. There are two or three on the terminal roof. The police are on their way."

The first flight out of Aberdeen was scheduled to leave at around 6.30am, the BAA spokesman said.

Plane Stupid said it was protesting against the airport's expansion plans and the resulting increase in greenhouse gas emissions.

The group said the activists were dressed as golfers in the style of US property tycoon Donald Trump, who is planning to build a major international golf resort in the area and supports the expansion of the airport.

One of the protesters on the runway, Dan Glass, 25, from Glasgow, said: "There are seven of us here who are fenced in. Two security guards are watching us, and have called for some more people."

He added: "We're here to say the expansion cannot happen, and our generation won't let it happen.

"The scientists tell us we've got seven years to make emissions peak then drop, and if we fail, the people on this runway and their entire generation, and our children, will live with the consequences. That's why we're doing this."