France's CGT union threatened to cut power to lawmakers and billionaires ahead of a nationwide strike Thursday over an increasingly bitter fight against the government's plan to raise the retirement age, Reuters reported.

The proposed bill, announced last week, would raise the retirement age from 62 to 64, which opinion polls show is opposed by an overwhelming majority of French people already facing a cost-of-living crisis.

Workers in sectors such as transportation, education and energy across France will take part in the strike Thursday, with major protest marches expected in Paris and other cities.

The strike is seen as a test of whether the unions, which in recent years have struggled to convince people to go on strike, can turn that anger into mass social protest.

Government spokesman Olivier Veran said that threats to cut off electricity are unacceptable.

Public transport will be hit hardest on Thursday: most trains, as well as some flights, have been cancelled.

Meanwhile, Interior Minister Gerald Darmanin said that more than 10,000 police officers will be on the ground during the protest marches.