MPs have called on the government to do more to reduce carbon emissions from existing homes.

The communities and local government committee warned on Wednesday that ministers had given "insufficient priority" to improving the green credentials of existing properties.

Current housing policy "risks neglecting the environmental impact" of more than 25 million homes in the UK's existing housing stock, said the report.

And pointing out that homes built at least 90 years ago emit nearly twice as much carbon as new ones, it called for more focus on making existing properties more energy efficient.

Committee chairman Phyllis Starkey said: "The government's understandable desire to build improvements into future housing has led it to give insufficient priority to action on the vast bulk of the housing stock.

"It clearly needs to engage as fully with reducing carbon emissions from the 25 million homes we already have as it has with cutting those from new development.

"We need a much clearer focus on what must be done to bring existing housing up to required energy efficiency standards."

She added: "The point will come when all the 'low hanging fruit' has been picked, by which I mean cavity walls filled, windows draft-proofed and boilers lagged.

"We need the government to go further and do much more to help householders radically cut carbon emissions from their homes, whether they were built in 2007 or 1707."

The report called on the government to work with local authorities to make home improvements, such as insulation, to make households more energy efficient, and do  more to help those in fuel poverty.

It recommended that minimum performance standards be set for existing homes as well as new builds, and said that energy performance certificates should be made more widely available.

"The bulk of our housing, however old and leaky it may be, is capable of the kind of improvement that will deliver the necessary reduction in carbon emissions without destroying the visual character that makes it uniquely ours," it said.

The news comes ahead of the carbon emissions reduction target, which comes into force this week and requires energy suppliers to improve efficiency for vulnerable customers.

Housing minister Caroline Flint said the government was "absolutely committed to reducing carbon emissions from both existing and new buildings and huge progress has already been made".

"The carbon emissions reduction target will remove the equivalent of 1.45 million cars from the road through promoting simple energy efficient measures in the home, and a green homes programme being launched today will provide a one-stop shop to support homeowners wanting to make environmental improvements," she said.

"We have the strictest timetable for reducing carbon emissions in new build homes anywhere in the world and by making the right changes to existing homes, we can make a massive contribution to reducing carbon emissions."