PARIS (Reuters) - France published a decree on Monday to prevent the planting of genetically modified maize as a stop-gap measure, while the government works on changes to domestic and European laws to ensure a longer-term ban.

The French government, which says GM crops present environmental risks, has been trying to institute a new ban on GM maize (corn) after a senior court twice struck down similar previous measures.

France also suffered a setback in the European Union last week when member states failed to agree on whether or not to approve a new GM maize strain, leaving the way open to the EU Commission to approve the variety for cultivation.

The government said its decree would come into force following a three-week consultation period that runs to March 9. Annual sowing of maize in France gets under way in the second half of March.

Monday's move was timed to avert any sowing of GM maize by farmers before a draft French law banning planting of GMOs (genetically modified organisms) is expected to be voted in April.

"This will prevent there being a period during which GM maize could be sown," a farm ministry spokesman said.

The French Senate started debating the proposed domestic law on Monday.

The current Socialist government, like its conservative predecessor, has opposed the growing of GMO crops in view of public suspicion and widespread protests from environmentalists.

Only one GMO variety is currently authorized for cultivation in the European Union - Monsanto's MON810 insect-resistant maize. A GM potato was cleared by the European Commission but later blocked by a court.

Longstanding differences between EU countries resurfaced last week when they failed to secure a majority either for or against the approval of another maize variety, Pioneer 1507, developed jointly by DuPont and Dow Chemical.

France is now trying to win support to overhaul EU rules.

It was one of 12 countries to sign a letter last week warning the Commission against approving Pioneer 1507. France is also trying to reach a common position with Germany ahead of a joint cabinet meeting in Paris on Wednesday.

"We need to give a legal framework to those countries that do not wish to see GM maize grown," French Agriculture Minister Stephane Le Foll told France Inter radio on Sunday.

France is turning to the idea of letting each EU country decide on whether to approve GMO crops, a solution previously blocked by member states but which the Commission has said it will revive.

(Reporting by Gus Trompiz, Sybille de La Hamaide and Valerie Parent; editing by Jane Baird)