The accusation was made after ministers revealed it will take 66 years to bring Scottish homes up to standard - compared with 10 under rival Green proposals.

Answers to questions about the Home Insulation Scheme also showed one-third of the £15 million allocated will be spent on administration.

And the project will miss the UK Government`s 2015 target on home insulation.

The scheme is a slimmed-down version of the Green`s £1 billion proposals to offer free insulation to all homes over a decade.

Dispute over the scheme derailed Finance Secretary John Swinney`s budget at the first time of asking in February.

Green co-leader Patrick Harvie MSP said: "We always feared that the Scottish Government's Home Insulation Scheme was being set up to fail, but the flaws with it are now clearly on a scale beyond even our worst fears.

"It seems that ministers are more concerned about justifying their political decision not to support Green proposals than actually providing insulation to cut people's bills."

A series of answers to Mr Harvie revealed no information is yet available on a loans scheme for hard-to-treat homes.

A pledge that ministers would attract an extra £15 million from other sources appears to have been cut to £750,000, the Greens said.

Mr Swinney said in February that the additional funds would provide 90,000 homes with advice and assistance in energy efficiency.

But Mr Harvie added: "Our priority was the delivery of actual insulation measures, and ministers still have no idea how many jobs will be done.

"Ministers promised Parliament that their scheme would entice a matching £15m from partner organisations, but they now admit that just a twentieth of that will actually arrive. Will they now at least make up the difference?

"Worst of all, our plan would have delivered warm homes all across Scotland by 2020, but the SNP's cautious approach wouldn't deliver this until 2075. Scots can't afford another 66 winters in cold uninsulated homes, yet this appears to be the SNP's approach.

"To say we're disappointed with the scheme so far would therefore be the understatement of the year."

A Scottish Government spokesman said: "The Home Insulation Scheme is intended as part of a long term process of improving the energy efficiency of Scotland's housing.

"Ministers announced on July 30 the 10 council areas that will be the first to benefit from this ground-breaking home insulation scheme, but there will be further opportunities for other local authorities to benefit in the future.

"This Government is determined to do all it can across Scotland to help make homes warmer, reduce fuel bills, safeguard existing jobs and create new employment opportunities."