Workers lift strike at BHP Billiton's Colombia nickel mine

BOGOTA, May 1 (Reuters) - Miners have ended a two-week long strike at the Cerro Matoso nickel mine in Colombia, after reaching agreement on a dispute that had force BHP Billiton (NYSE: BBL - news) to declare force majeure earlier this week, the company said on Friday.

Unionized workers had been blocking access to the ferronickel mine and refinery since April 14 in protest at a change to longer shifts they say will increase uninterrupted exposure to toxic substances and damage their health.

The company said in a statement that it will now suspend that decision except for non-mining workers, but it would still seek to implement it within 30 days with monitoring and advice on potential health issues from the Labor Ministry.

"Once operations are normalized and in a more complex financial scenario, the company will resume its productivity drive begun in 2014, continuing with measures to lower costs," the statement said.

Union leader Domingo Hernandez confirmed the agreement and said operations would be back to normal from 11 p.m. on Friday (0400 GMT Saturday) when a shift that starts at that time would resume.

The company switched to two daily 12-hour shifts from three eight hour stints previously in order to boost productivity by reducing lost working time through fewer handover periods.

BHP had restarted some production last week by flying some workers in by helicopter, thereby averting a risky shut-down of its furnaces, but volumes were minimal and it was forced to advise clients of possible defaults on deliveries.

Cerro Matoso's Luis Marulanda, vice president of external affairs, told Reuters on Thursday that a judge had given workers 48 hours to end the blockade this week though the union said it had not received any such notification.

Cerro Matoso is one of the assets that form BHP's proposed spin-off company South32.

LME nickel was set to log 5 percent gains this week, matching last week's rise, as short-holders covered despite ample supplies in the market. (Reporting by Carlos Vargas and Peter Murphy; Editing by Simon Cameron-Moore)