The French government on Wednesday started ordering staff at an Exxon Mobil fuel depot back to work, striving to secure petrol supplies following weekslong strikes but risking a wider conflict with trade unions.

The government said it was requisitioning staff at the Gravenchon-Port Jerome depot run by Exxon's Esso France business, where the hardline CGT union remains on strike despite an agreement between management and other unions over pay.

The CGT has called for support from workers in other sectors and there were signs of that happening after a representative of the FNME union said some staff at EDF's nuclear plants had resumed a strike over wages, delaying maintenance work on at least five reactors, including the Bugey facility.

"In view of a strike by part of the Port-Jerome staff, in Normandy, the government launches the requisition of staff necessary to operate the depot. The requisition is starting today," the Energy Ministry said.

The CGT said it would challenge the requisition notifications in court once it had received them.

After shying away at first from interfering in labor disputes pitting the CGT against oil majors TotalEnergies and Exxon, the government on Tuesday threatened to force staff at Esso France depots back to work and said similar measures were possible at TotalEnergies if wage talks failed.

The strike at TotalEnergies' French refineries resumed across all sites on Wednesday, the CGT said.

In the nuclear sector, FNME representative Viginie Neumayer told Reuters the union had sent a message of support to striking workers at refineries and petrol depots owned by TotalEnergies and Exxon.

"The threat of requisition which is above all a sign of government feverishness has never demonstrated its effectiveness in getting out of this conflict," Neumayer said.