Longannet power station is operated by Scottish Power

Longannet power station in Fife appears at number 17 on a list of the least efficient among the biggest emitters of carbon dioxide.

The report said that 27 of the 30 dirtiest power plants were coal-fired.

Operator Scottish Power said the plant was well within EU and British guidelines for emissions.

The firm said that the continued use of coal-fired power was a legacy of the past.

This generation of coal-fired power station will come to an end in the next decade Scottish Power

It said Scottish Power was the biggest generator and developer of wind energy in the UK.

A spokesman said: "This generation of coal-fired power station will come to an end in the next decade.

"In the meantime, the most effective thing to do is to build-up renewable energy sources and run our existing coal power stations as efficiently as possible."

Five of WWF's "Dirty 30" power stations were in Germany.

Longannet was the highest placed UK plant.

What we'd like to see is development of Scotland's massive renewables potential Dr Dan Barlow WWF Scotland

Head of policy for WWF Scotland, Dr Dan Barlow, told BBC Radio's Good Morning Scotland programme that inefficient stations should be phased out.

He said: "What we'd like to see is development of Scotland's massive renewables potential, Scottish Power are already investing in renewables and there's much more that could be done to further that.

"And there are also options including gas which are much more efficient than coal and we'd like to see those options being used as replacement mechanisms."

Dr Barlow called on stricter limits to be set on the emission trading system which creates carbon dioxide quotas.