PARIS, Oct 24 (Reuters) - France is considering banning the use of the sole genetically modified crop grown in the European Union, a maize produced by U.S. biotech giant Monsanto, Agriculture Minister Michel Barnier said on Wednesday.

President Nicolas Sarkozy will unveil on Thursday a new environment policy based on a series of meetings bringing together government, environmentalists, scientists and business leaders.

One of the remaining uncertainties at this stage is whether Sarkozy will allow GMO crops to continue to be grown for commercial use in France or if he will decide to ban them.

Only one GMO crop is grown and sold in the European Union, the so-called MON-810 maize, but Monsanto must request a renewal of its licence early in 2008.

'The question is, since this authorisation will fall due in April, in a few months, whether it will be suspended and for how long. It will be the President who will decide,' Barnier said on France Info radio.

Speaking to Reuters during a visit to Paris, European Agriculture Commissioner Mariann Fischer Boel said that any such move by France would clearly go against the rules.

'That would not be legal,' she said. 'We've seen in Upper Austria where they banned it as well and it has ended up in a court case and they lost. So France will lose if they ban it.'

Farmers could choose to use or not use GMO seeds on a voluntary basis, she added.

Austria is one of the 27-nation bloc's more sceptical countries when it comes to GMO foods and may soon face a third attempt by EU regulators to force it to lift bans on two GMO maize types.

Countries worried about GMO seeds contaminating traditional or organic crops could protect themselves by implementing strict and clear legislation to prevent such a phenomenon, she said.

Just 22,000 hectares -- 1.5 percent of France's cultivated land -- have been sown with Monsanto's GMO maize this year but some farmers have urged greater use of GMO crops to boost yields.

Only the European Union has the power to authorise commercial sales of GMOs in the bloc but a member state may ban a crop in its own country, using a 'safeguard clause'. It then has to notify and justify its move to the European Commission.

Barnier also said that the measures put forward in the environment package would allow open-field tests to continue, despite fierce opposition by anti-GMO groups, in a bid to support research.

'We absolutely need research, including open-field research, with all the required precautions, not to be dependent, in 10 or 15 years, on Chinese or U.S. research,' he said.

'It's a question of sovereignty, for Europe and for France.'