OSLO (Reuters) – Norwegian oil workers expanded their ongoing strike on Monday, the Lederne labour union said, in an escalation expected by energy firms to shut oil and gas production at up to six offshore fields.

The escalation could reduce Norway’s petroleum production capacity by as much as 330,000 barrels of oil equivalent per day (boepd) or 8% of the country’s total output, the Norwegian Oil and Gas Association (NOG) had said.

The conflict began on Sept. 30 when a group of 43 workers organised by the Lederne union went on strike, but did not initially impact oil and gas output.

“There is no solution in sight,” said a spokesman for NOG, which negotiates wage deals on behalf of the oil industry.

The escalation added a further 126 union members to the ongoing strike, taking the total number to 169 out of 1,003 offshore workers represented by Lederne.

Output from six fields could immediately shut, the NOG has said, including Equinor’s EQNR.OL Gudrun, Gina Krog and Kvitebjoern fields, as well as Kvitebjoern’s satellite Valemon field.

The Neptune Energy-operated Gjoea field and its satellite Vega field, operated by Wintershall Dea [WINT.UL], will also likely shut, according to NOG.

Equinor, Neptune and Wintershall Dea did not immediately respond to requests for comment when contacted by Reuters.

An Equinor’s spokesman told Reuters on Sunday that the company would have to start shutdown procedures at Gudrun, Gina Krog, Kvitebjoern and Valemon if the strike went ahead.

It can take several hours for a field to safely halt output.

“Employers are still showing no willingness to meet our demands, thus triggering the escalation,” Lederne trade union chief Audun Ingvartsen said in a statement.

Lederne said it was seeking better financial terms for its members and wanted the offshore wage agreement to also cover workers at onshore remote control rooms.

Equinor and other oil companies have been looking into ways to remotely control production at offshore fields to reduce costs.

NOG said Lederne’s demand fell outside the scope of the offshore wage agreement.