BOGOTA May 15 (Reuters) - Colombia's Trasandino pipeline is forecast to remain offline until December, the chief executive of Colombia's majority state-owned energy company Ecopetrol said on Wednesday.

Earlier this month, while reporting its first-quarter financial results, Ecopetrol said it had been transporting crude oil through Ecuador since November in order to combat oil theft.

Thousands of barrels of oil are stolen daily in Colombia. The crude is taken to clandestine refineries where it is converted into a bootleg fuel known as pategrillo, or "cricket's foot," and then used in cocaine production or illegal mining.

To combat theft on the Trasandino, which runs from Putumayo province to the Pacific coastal city of Tumaco, the pipeline is expected to remain shut this year while staying under evaluation, Ecopetrol CEO Ricardo Roa told Reuters.

The decision to stop pumping through the pipeline followed an increase in theft, Roa said, explaining that up to 20% of oil pumped via the Trasandino, equivalent to some 3,000 barrels per day, was being stolen.

Since Ecopetrol switched to pumping oil through Ecuador, losses have fallen to 0.3%, Roa said.

Earlier this month, Ecopetrol signed a contract with its Ecuadorean counterpart, Petroecaudor, to transport up to 22,000 bpd through the neighboring country's pipelines.

Reuters visited a destroyed clandestine refinery near Colombia's Pacific coast in November 2022, when oil theft from the Trasandino pipeline averaged just under 1,000 bpd.

Roa on Wednesday spoke on the sidelines of the inauguration of a resin recycling plant in Tocancipa, near the capital Bogota.

The $20 million plant is operated by Ecopetrol subsidiary Esenttia and is expected to recycle 12,000 metric tonnes of plastic resin per year. (Reporting by Oliver Griffin; editing by Jonathan Oatis)