France's referendum on a European Union constitution could take place in late May or early June, Justice Minister Dominique Perben said on Sunday, offering the most precise timetable to date. "The perspective is what we have always said -- end of May, beginning of June," Perben told French radio station Radio J, adding French President Jacques Chirac would make the final decision on the date. The French popular vote previously was expected by July. The date cannot be set until the French Parliament revises the French constitution. Perben said this could happen in March. "The ideal calendar would be that the text was approved by the Senate in the coming days, and that the congress could meet in the second two weeks of March," Perben said. EU leaders agreed to the wording of the constitution last June but it needs to be ratified by all 25 member states to come into force. The constitution is designed to make the EU function more smoothly after its expansion to 25 members from 15. French politicians worry people will vote against the constitution to voice their disapproval of France's conservative government, whose plans to revamp working conditions, health care and education have sparked strikes. Spaniards will on Feb. 20 be the first to hold a referendum on the constitution approved by EU leaders last year. Each of the 25 member nations has to ratify the charter though not all are planning referendums.