French rail travelers endured more misery Thursday as strikes cut train services by half, but a militant union's bid to widen protests against planned labor changes involving air traffic control and the Paris Metro appeared to fail.

In an unrelated dispute over pay, Air France pilots called a strike for June 11-14, coinciding with the start of the monthlong Euro 2016 soccer championships, which France is hosting.

The Socialist government refuses to scrap the labor measures despite fears that the standoff could disrupt Euro 2016, which kicks off on June 10.

Prime Minister Manuel Valls has rejected demands that he scrap a bill that the large and militant CGT union says will undermine labor protection by giving firms more scope to set in-house deals on pay and terms.

"If we gave in to the CGT, it would no longer be possible to reform France," Valls told the Ebra regional newspaper group.

His government, which insists the reform is needed to fight high unemployment, has been struggling to defuse sectoral tensions and prevent grievances coalescing into one big national protest.

On Friday, French high-speed train services will be cut by 40 percent and other inter-city links by two thirds, said the state-owned SNCF railway firm, a CGT bastion.

However, the smaller UNSA union pulled out of the strike after government assurances of help with the SNCF's 50 billion euro ($56 billion) debt, removing another strut of CGT support.

"You always know when a strike movement begins but you never know how it finishes," said Elvis Thoyer, a CGT rail union worker marching among a thin crowd of protesters in Paris.

In the western city of Nantes, a small number of hooded youths on the fringes of street protests smashed shop windows just as President Francois Hollande told mayors that political debate should "never be brutal and violent."

About 1.5 million foreign fans are expected to converge on France for Euro 2016.

The threatened strike by Air France pilots, which has little directly to do with the broader labor unrest and the sometimes violent street protests it has spawned, compounds the risk of chaos when all eyes will be on France.

"Our organization has to be exemplary to support Paris' candidacy for the 2024 Olympic games," Hollande said, looking further down the road. "We have to succeed."

Transport Minister Alain Vidalies said traffic ran normally on the Paris Metro despite a strike call while unions called off an air controllers' strike after government promises to keep staffing at current levels for the next three years.

CGT-led stoppages caused limited disruption at refineries and nuclear power plants but the union looked increasingly isolated in its efforts to force the government to withdraw reforms that would make hiring and firing of workers easier.

An Ifop poll for Le Figaro magazine showed 60 percent of French people believe the CGT is abusing the right to strike.

In a series of CGT publicity stunts, energy workers cut power to the town hall of Tulle, Hollande's political fiefdom, and switched more than a million homes in the Paris area to low-cost power supply.

Union members in the southern Var region also cut off power to the vacation home of employers' leader Pierre Gattaz after he accused protesters of behaving like "thugs," the CGT said.

In an attempt to shore up public support, the government this week announced pay rises for state-employed teachers and pledged to restore scrapped public spending for research.

It also intervened to force SNCF management go some way toward meeting union demands that rest-time be protected in a reorganization being discussed ahead of a Europe-wide opening of passenger rail services to private competition from 2020.

With presidential and legislative elections a year away, the concessions to teachers could help repair damaged relations with a sector generally sympathetic to the ruling Socialists.