BP said on Tuesday the planned restart of its large refinery in Rotterdam was on hold after unions said they would not help with the return to service due to a dispute over pay.
The refinery was shut last week due to technical problems.
"We regret the unions have decided to proceed," BP said in a statement, referring to the unions' warning on Monday that they would not cooperate with a restart unless BP changed its position on pay.
"As a result, the planned restart has been put on hold and operations at the refinery remain shut down," BP said.
Union spokesman Jaap Bosma said workers were still present in the refinery and performing tasks needed to keep equipment undamaged and in working order.
"We asked in a technical discussion how BP would react if workers are not performing certain tasks, and they didn't know yet either," Bosma said.
"We presume that for now they will continue to pay wages."
A spokesperson for BP declined to answer questions beyond the company's statement and could not say how long the refinery closure might last.
Discussions over a new collective labour agreement have been ongoing since April. Unions are seeking a package representing a 9.5% pay increase, plus a one-time bonus, while BP has offered a 5% increase and a one-time bonus. Dutch inflation is around 15%.
"We do remain in dialogue with the unions to reach an agreement and minimise the consequences," BP said.
BP's Rotterdam Refinery processes about 400,000 barrels of oil per day.