The UK government was today again accused of seeking to water down the EU's package of climate change regulation after it emerged that officials at the Department for Business Enterprise and Regulatory Reform (BERR) were lobbying for aviation to be excluded from renewable energy targets.

Under the proposals, aviation is to be included in targets to ensure 20 per cent of Europe's energy mix comes from renewable sources, paving the way for far wider use of biofuels by airlines.

However, documents leaked to the BBC show that the UK is leading attempts to have aviation excluded from the targets on the grounds that aviation biofuels are still at an early stage of development and it will be difficult for the industry to produce enough biofuel in a sustainable manner.

The document says that "member states want the aviation sector to be excluded from the denominator used to calculate the overall target. They consider that in the present state of technology we cannot expect it to be possible for biofuels that can replace kerosene to be certified for commercial aviation by 2020."

But environmental groups countered that the target would not require aviation to source 20 per cent of its fuel from biofuels, but would instead require other sectors to cover any shortfall by increasing their reliance on renewables.

They argued that exempting aviation from the target would effectively mean that the overall target for the EU economy would be reduced from 20 per cent to 18.5 per cent.

Friends of the Earth energy campaigner Robin Webster accused the government of "acting disgracefully" by attempting to "wriggle out" of the targets. “EU renewable energy plans are an essential part of its climate change strategy," he said. "Ignoring aviation would be like going on a calorie-controlled diet but refusing to count calories from chocolate."

The government's contention that the aviation industry would struggle to make significant use of biofuels by 2020 was also disputed by aviation industry experts, with a spokesman for Virgin Atlantic telling the Guardian newspaper that it expected to run 10 per cent of its fleet on biofuels by 2020.

In an unusual move, Claude Turmes, the MEP leading the development of the renewable energy legislation for the European parliament, openly criticised the UK government for attempting to water down the targets.

"I find it outrageous," he told the BBC. "Prime minister Brown came here and said he would stick to the 20 per cent. [But] now his civil servants in Brussels are not following that. They are trying to dilute the target in the directive – they are attacking it."

However, a spokeswoman for BERR insisted that while the government remained committed to meeting the EU targets it made sense to exempt aviation from the renewable energy goal, adding that its inclusion in the EU's emissions trading scheme would ensure that the sector made a contribution to tackling climate change.

"The UK believes the renewables target should apply to sectors where renewable energy can be realistically rolled out within the next 12 years," she said. "Aviation is already excluded from the 10 per cent renewable transport target – which also forms part of this directive – because biofuel technology for aircraft is many years away."

The leaked documents also revealed that the UK is lobbying to have rules that would require renewable energy technologies to be fitted to all new and refurbished buildings scrapped, and is seeking to dilute further the 20 per cent goal by allowing renewables projects that have started by 2020, but are not yet complete, to count towards meeting the target.

The news comes hot on the heels of revelations last week that UK officials were also lobbying to increase the extent to which European governments could use investment in carbon reduction projects in the developing world to count towards domestic emission reduction targets.