Prime Minister Gordon Brown has been accused by a think tank of failing to harness his economic stimulus for the benefit of the environment.
The New Economics Foundation says that among rich nations, the UK has invested the least in clean technology.
It called UK performance pathetic, but the Treasury said the fiscal stimulus could not be looked at in isolation.
It said it expected to drive over £50bn of investment in the low-carbon sector between 2008 and 2011.
Meanwhile, three other reports out on Monday call for world leaders to use the financial crisis to create a new economy that benefits the environment.
They say the world financial stimulus package can improve security for energy, food and water supplies if it is invested wisely.
The analysis by the New Economics Foundation (NEF) criticises the UK for spending just over £100m - 0.0083% of its national wealth (GDP) - on genuinely new and additional measures to benefit the environment.
Andrew Sims, the report's author, said: "This is a fraction of the amount given to RBS staff in bonuses. The prime minister says he is creating green jobs but this is a fantasy. The government's performance is pathetic."
A Treasury spokesman said it was unfair to look at the green element of the fiscal stimulus in isolation.
He said: "The UK already has a comprehensive policy framework in place, expected to drive over £50bn of investment in the low-carbon sector between 2008 and 2011, including supporting renewable energy, upgrading grid infrastructure, enhancing energy efficiency and improving public transport.
"This must be considered when comparing different countries' approaches to low-carbon investment and the development of a low-carbon economy."
Meanwhile Lord Stern, a former UK Treasury chief economic adviser, is launching a report commissioned by the German government.
It calls for massive investment by the G20 nations in energy efficiency and new electricity grids; supporting markets for clean technology; pushing up the price of emitting carbon; and initiating large-scale demonstration projects for carbon capture and storage and concentrated solar and energy storage.
His study expresses confidence that G20 leaders can build a low-carbon economy which brings the world back on track for growth and prosperity.
In the UK, a report by Greenpeace, the Federation of Master Builders and the Liberal Democrats accuses the government of missing an open goal by creating jobs through new roads and subsidies to car firms when the cash could have been spent on more insulation.
They say this creates more jobs for the money, while also cutting energy demand and emissions.
'More work needed'
The report says the government's new green measures will delay the growth of UK carbon emissions by five-and-a-half-hours by the end of 2011.
Another report, this time by HSBC, suggests that South Korea and China have spent more than 1% of their GDP on green growth.
Pavan Sukhdev, the banker who heads the UN's green economy drive, told BBC News: "The UK needs to recognise this is a competitive situation.
"They need to compete into the future where there will be a cost for carbon, there will be low-carbon development models in rich and poor nations, and the UK will do itself and its entrepreneurial community an injustice if it does not provide them with at least the same competitive position that the rest of the world has.
"I think a bit more work is needed with Prime Minister Brown."