Adds impact on oil production, Safe comments, quotes in paragraphs 2-3, 5

OSLO, June 22 (Reuters) - Norwegian oil service companies will impose a lockout from June 27 in response to an ongoing strike over wages by workers represented by the country's Safe labour union, the industry group representing employers said on Monday.

Offshore Norway said in a statement that although the strike has so far not had an immediate impact on the country's oil and gas output, it had resulted in "somewhat postponed production".

"The lockout will further delay drilling operations already affected by the strike, with at least two rigs having halted work," a group spokesman said, adding it was difficult to quantify the potential impact on delayed production.

Safe launched the strike on June 15 after failing to reach a wage agreement, while another union, Styrke, accepted the offer.

"We are ready to take this fight further to ensure a fair result in the well service agreement," Safe's deputy leader Kai Anda said on Monday.

STRIKE COSTLY FOR EMPLOYERS

The union escalated the action on June 18, bringing the total number of striking workers to 378 and affecting companies including SLB SLB.N, DOF Subsea, Halliburton HAL.N, Weatherford, Tios and DeepOcean.

Offshore Norway said the strike has imposed high costs on supplier companies, prompting them to implement the lockout.

"This is a legal instrument within the collective bargaining system and is used to help bring the conflict to an end," it added.

The lockout would affect 1,272 Safe members out of some 1,770 covered by the wage deal, while exempting some workers to maintain safety-critical subsea emergency preparedness.

The government can force the parties to reach a deal, but Anda said Safe didn't see this happening as of yet.