Unions have told Exxon they intend to strike on Nov. 23, as the company has refused to start talks about improved pay conditions.

"We have no other choice as long as the strike notice still stands," a spokesman for Exxon Belgium said, adding plans to safely shut down the refinery were going ahead.

The BBTK union said talks with Exxon had started, and could last until the early hours of Saturday.

A spokesman for the union said if Exxon agreed to accept a list of union demands, then the strike threat could be removed.

France's Total denied that the strike threat had spread from Exxon to its own 360,000 barrels per day refinery in Antwerp.

The head of personnel at the refinery said management had reached a deal with unions on Thursday. "This is purely an Exxon issue," she said.

Exxon's Antwerp refinery has a capacity to process 320,000 barrels per day of crude oil, the group said.