The Defra-funded, independent company said this would enable SMEs to implement energy saving projects on a more ambitious scale.

Carbon Trust solutions director Hugh Jones said that in the current economic climate, tighter credit conditions are making it harder for small businesses to find alternative sources of funding.

"Some companies found the previous £100,000 limit made it hard for them to finance the more ambitious projects they wanted to invest in, such as large light installations or boiler projects," he said.

"£200,000 loans pave the way for companies to take on such projects and significantly reduce both their carbon emissions and their energy bills, making them reduce operational costs and become more competitive."

It is expected the new scheme will generate 20% more carbon and energy savings this year.

The loans are unsecured, interest-free and repayable over a period of four years. They are available to SMEs in England and Scotland, or all businesses in Wales that have been trading for at least 12 months.

Businesses in Northern Ireland that have been trading for 12 months could be eligible for loans up to £400,000.

The Carbon Trust is funded by Defra, the Department for Business, Enterprise and Regulatory Reform, the Scottish government, the Welsh Assembly and Invest Northern Ireland.