A 24-hour strike has stopped oil rigs and affected well maintenance at Ecopetrol’s La Cira-Infantas oil field, the Colombian state-run company and the USO union said on Sept. 6.

Ecopetrol said production at wells had not been affected, though 19 drilling rigs had been halted.

Those striking are all employed by contractors, the company and union said. Ecopetrol has 9,000 direct employees nationally, while its contractors employ some 25,000 people.

The Petroleum Industry Workers Union (USO) said some 2,300 workers were participating in the strike, which began at 6 a.m. local time and is set to last 24 hours.

USO is in the midst of contract talks with Ecopetrol after its salary and benefits agreement expired in June. That deal remains valid until a new one is signed.

The union has 18,000 members across the Andean nation, whose top export is oil, and is planning a series of strikes around the country ahead of a Sept. 22 deadline for the new deal.

If no deal has been reached by that date, the union can go to arbitration with Ecopetrol or hold a national walk-out, union president Cesar Loza said.

“The strike is part of a mobilization plan that the union has. Later we’ll be holding other mobilization actions in refineries and at pipelines, depending on advances at the negotiating table,” he said, adding the union did not want to go to arbitration.

Ecopetrol said in a statement it rejected the strike.

“The union also promoted blockades in different access points where direct employees of Ecopetrol and contractors who work at the field travel,” the company added.

La Cira-Infantas, in central Santander province, has an average daily production of 45,000 barrels, Ecopetrol said.