When President Chirac pledged three years ago to launch a national debate on the future of education, he could not have foreseen the furore he would spark before the reforms even took effect.

Parliament approved education minister Francois Fillon’s laws in March, with the first measures due to take effect in September. But now the Constitutional Council has rejected two key clauses, and lycee pupils, teachers’ unions and parents’ representatives are continuing their bitter protests against the Act.

The reforms are intended as a landmark change from a “child-centred” education system to one providing a “common base of skills” and a minimum qualification for all pupils. They were introduced after a nationwide public consultation, but failed to win over the educational community.

Mr Fillon had already been forced to withdraw plans to change the baccalaureat school-leaving exam after demonstrations by 100,000 pupils.

Despite this climbdown by the minister, protests have continued, sometimes turning violent through riots caused by outsiders. In April Mr Fillon allowed the police to use force, including teargas, to evacuate occupied schools.

More than 160 lycee pupils were arrested after occupying an education ministry in Paris. So far nine have been charged with violence against police and damage to property, and face up to three years in prison and fines of 45,000 euros (pound;30,000).

Now the government faces a ruling by the Constitutional Council that says that Article 7, defining the missions of the education system, failed to set clear standards and therefore had no legal standing.

Another clause approving budgetary programmes was rejected on the grounds that they were covered by economic and social law and, under the constitution, should therefore be submitted to the Economic and Social Council.

Gerard Aschieri, of the FSU teachers’ federation, said that the ruling meant that Mr Fillon could no longer argue that he had the legal high ground, and would have to “start again from zero and hold genuine negotiations rather than persist in introducing something nobody wants”.

But Mr Fillon said he was satisfied that the council had validated “87 out of 89” reform measures. He insisted that he could restore the rejected elements through statutory decrees and circulars.

The Constitutional Council, set up in 1958, has nine members who serve for nine years and are selected by the presidents of the Republic, the National Assembly, and the Senate. Even though the council is the highest constitutional authority in France, it can act only if legislation is brought to its attention before it becomes law.