The refinery is being upgraded with an investment of $6.4bn, to expand its refining capacity to around 165,000 barrels per day.

After completing the upgrade, the facility would take around five months to reach the expected production rate, the company said.

Ecopetrol refining and industrial processes vice-president Pedro Rosales was quoted by Reuters as saying: "We’re already in the final phase of construction … These activities should permit the refinery’s operation to commence by October or November."

All the 31 units of the refinery will be brought online in phases.

"It’s a process that has to be conducted carefully for security and efficiency reasons, and the complete process could take between three and five months," Rosales added.

The complex features crude and visbreaking units, fluid catalytic cracker, and light products, polymerization, amine, sulphur, and impurities treatment plants.