A leading climate change scientist from NASA has called on the First Minister to put plans for new coal-fired power stations on hold.

Dr James Hansen says they should only be built if they are fitted with technology to capture and store the greenhouse gas, carbon dioxide.

Ministers are backing the development of new coal-fired power stations as long as they are "ready" to add the technology at a later date. Dr Hansen stated his concerns in a letter to Alex Salmond.

"Carbon capture and storage readiness is not an adequate solution," the scientist said.

"It is a sham that does not guarantee that a single tonne of carbon will be captured in practice. Alternative approaches must be considered which ensure an effective moratorium on new unabated coal power."

He added: "This is an opportunity to demonstrate world leadership and impose a moratorium on new coal fired plants until such time as any new plant can be guaranteed to operate with full capture throughout its entire life."

Dr Hansen's evidence on climate change to US congressional committees in the 1980's helped raise broad awareness of global warming. He has also advised the US Government on the issue.

Scotland has a target of reducing greenhouse gas emissions by 80% by 2050. Carbon dioxide from coal-fired power stations currently account for almost 20% of the country's CO2 emissions.