French Prime Minister Manuel Valls refused on Monday to yield to the demands of rail workers on strike for close to a week against a planned reform of the sector.

The strike, to continue on Tuesday, is one of the longest France has seen in years and has disrupted services since it began on June 10, testing the resolve of President Francois Hollande’s government to push through sometimes unpopular reforms.

Unions CGT and SUD are against plans, intended to prepare the sector ahead of EU reforms aimed at bringing more competition to European transport routes, while less militant unions have dropped their opposition and returned to work.

The government and state-owned SNCF have had to mobilise special train and bus services to ensure students can attend annual end-of-school exams beginning on Monday for hundreds of thousands of students across the nation.

“This strike is irresponsible in the country’s (current) state, on a day of exams. It’s time to stop this strike,” Valls said on France Info radio.

Insisting the government would push ahead with the reform, he said that he was “no strike-breaker” and would not force unions to end the strike, which he said they had a constitutional right to carry out.

The strike - which SNCF railway chief Guillaume Pepy said had so far cost 80-100 million euros - continued to cause significant disruption, with many high-speed TGV connections cut by 50 percent and only four in 10 inter-city trains operating.

There were signs of weakening resolve however, with the percentage of railworkers on strike down to 14.7 percent on Monday, half of the level at the outset last week.

Parliament is due to begin debating a bill on Tuesday that would bring the SNCF rail operator and RFF network owner into the same holding company, although their operations would be kept separate.

Hollande’s Socialist government says the move would give the sector a more coherent structure as France and other European countries prepare for liberalisation.

Unions fear that working conditions would suffer and want SNCF and RFF to be fully merged into one entity as they were prior to 1997. They also want the state to take on 40 billion euros ($55 billion) in debt owed by the firms.