The UN special rapporteur on the right to food urged the EU for a rethink on biofuels Friday, saying huge errors had been committed in the initial enthusiasm for an alternative to harmful fossil fuels.

"The more biofuels the EU produces, the more it will be forced to import vegetable oils from the rest of the world," said Olivier De Schutter.

As the European Commission prepares to release a report on the question early next year, the UN expert admitted it would be difficult to turn back given the huge investments made by farmers attracted by pledges of a booming biofuel market.

With the European Union committed to producing 10 percent of its energy in renewables by 2020, massive investments have also been made in buying land in Africa to produce sugar or sweet potatoes for biofuels.

"We may have to fundamentally rethink this policy," he said at a Brussels press conference.

Officials, experts and scientists were increasingly underlining errors made in the past few years in backing biofuels.

Headlined as a magic solution to global warming, it was now surfacing that biofuels "are not an efficient way of reducing greenhouse gases," he said.