"There will be more analysis but we don't have any clear answers," Slovenian Prime Minister Janez Jansa told a press conference after the first day of an EU summit in Brussels.

"I'm not excluding the possibility that we will have to revise or amend our goals," he said.

The 27-nation EU aims to ramp up its use of biofuels in coming years after the bloc's leaders set tough renewable energy targets last year.

They committed to increase the EU's renewable energy use by 20 percent by 2020, compared to 1990 levels, with biofuels to make up 10 percent of all transport fuels used by then.

However, since EU leaders fixed those targets in March last year, concerns have risen about possible negative effects from biofuels, including their impact on food prices and the environment.

Italian Prime Minister Romano Prodi was among those voicing doubts on Thursday, telling his fellow EU leaders of his concerns over the need to switch land currently producing food crops to growing biofuel crops such as colza.

Last week the UN agency in charge of alleviating world hunger warned the European Union that the fast-growing use of biofuels is driving up food prices for the world's poor.

"The shift to biofuels production has diverted lands out of the food chain," World Food Programme executive director Josette Sheeran told lawmakers at the European Parliament in Brussels.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.