France's troubled energy sector suffered another setback on Thursday as a 24-hour strike reduced the country's nuclear and hydroelectric output.
Electricity workers went on strike on a day of protest called by trade unions demanding higher pay and opposing President Emmanuel Macron's plans to raise the pension age.
Although some unions sat out the nationwide strike, it was potent enough to cut nuclear power generation by 3.5 gigawatts and hydropower output by 470 megawatts.
More than half of France's oil refining capacity is offline due to strikes, Reuters reported, after the walkouts hit TotalEnergies refineries for a third day.
It comes against the background of corrosion problems and closures for maintenance that have plagued France's usually prolific fleet of 56 nuclear plants.
French estimates suggest output will remain disappointing into January and February, further squeezing Europe's energy supplies at a time when gas is at a premium.
The problems have made France a net electricity importer from Germany for the first time in decades, potentially forcing Berlin to postpone its own nuclear switch-off to generate enough power.
The strike on Thursday was followed by about one in 10 teachers walking out, the Education Ministry said, leading to school closures in some areas. One in three railway workers also stopped work, the CGT union said.
Despite the strikes, Mr Macron's government indicated on Thursday it would press ahead with the pension reforms that were a central talking point in his re-election campaign this year.
Talks with political leaders and unions will start as early as next week and ministers hope to put the pension reforms to a vote in early 2023, Labour Minister Olivier Dussopt told LCI television.
Mr Macron's centrist party lost its majority in the French Parliament in June after left-wing parties who oppose the increase in the pension age banded together to weaken the president.
"All the unions in France are against working up to 64 or 65, because it's stupid," the head of the CGT union, Philippe Martinez, told France 2 television.