"The government is at work to try to find a way toward a rapid compromise," spokeswoman Sibeth Ndiaye told France 2 television as Prime Minister Edouard Philippe gathered ministers for the unscheduled meeting.

Unions have roundly rejected plans to scrap France's 42 separate pension regimes for a single points-based system, which they say could require millions of people to work beyond the official retirement age of 62.

President Emmanuel Macron made the reform a key plank of his election campaign, saying it would be more transparent and fairer, in particular to low earners and women.

Yet the government has already announced a series of concessions to certain sectors, such as police officers and military personnel, pilots and rail employees.

Many other public-sector workers are demanding similar exceptions to the new rules, which would set a "pivot age" of 64 which people would have to work until to receive a full pension.

The hard-line CGT union has called for a four-day blockade of the country's fuel refineries and depots starting Tuesday, when talks between unions and the government are to resume.