A report issued by the Renewable Fuels Agency put biofuels use in the first two months of the programme at 2.53 percent.

Britain produced only 10 percent of the biofuel, well behind the world's two leading producers United States (27 percent) and Brazil (15 percent) while the origin of 32 percent of the fuel was classified as unknown.

Biofuels, which are currently mainly produced from grains, vegetable oils and sugar crops, are seen as a way to reduce dependence on fossil fuels and cut emissions of the greenhouse gases believed to contribute to climate change.

Britain does not currently require that environmental standards are met and critics fear that expanding production of certain feedstocks such as palm oil contributes to to rainforest destruction in southeast Asia.

"This data shows that biofuel importers are pretty much in the dark when it comes to the origin of their products," said Mariana Paoli, forest campaigner for Greenpeace. "Government targets were set too hastily, and are currently allowing all sorts of unsustainable biofuels slip through the net.

"No further targets should be pursued until much tougher sustainability standards, including both direct and indirect land use effects, have been put in place."

MULTIPLE ORIGINS

Alex Lewis, spokeswoman for UK-based biofuels supplier Greenergy, said some of the unknown origin material was likely to be rapeseed from the European Union.

The RFTO does not recognise EU as an origin but shipments can be comprised of rapeseed from more than one country within the trading bloc, she said.

Britain's Environmental Industries Commission, an industry group, said the high levels of imports was not surprising.

"They (Britain) are creating demand but not enough clarity for people to go out and get investment. So this is what we predicted," EIC director Merlin Hyman said.

"The problem with relying on imports is they are that much harder to guarantee any sustainability criteria," he added.

Britain announced in July it plans to slow the introduction of biofuels to address concerns that switching the use of land could exacerbate climate change and push up food prices.

Biodiesel account for 78 percent of the renewable fuel and bioethanol 22 percent.

The most important feedstock for biodiesel was soy, mostly from the United States, while the bulk of the bioethanol was produced from Brazilian sugar cane.

(Reporting by Nigel Hunt; Editing by Michael Roddy)