Chevron, which owns the Texaco filling stations brand, is allowing 24 months for the sale but told Sky News it could not rule out shutting the site down.

The company can currently process up to 220,000 barrels of oil a day at the Milford Haven site in Wales, one of the company's eight refineries around the world.

Chevron made the move as it looks to concentrate its marketing and refining - or "downstream" - operations in North America and Asia Pacific.

The company is inviting bids for refineries in the Caribbean and Central America.

Operations in Hawaii and Africa, outside South Africa, are also under review.

Separatetly, Chevron said it was looking to cut 2,000 staff worldwide this year.

It is not known how many UK workers will be affected by those cuts.

In a statement, the company said: "Chevron has announced its intention to solicit bids for some of its operations in Europe as part of the company's global downstream restructuring.

"This includes our Pembroke refinery, as well as fuels marketing, aviation and lubricants operations in Europe.

"No decision has been made to sell any asset at this time.

"Our continuing focus is on operating Pembroke refinery in a safe, reliable and environmentally responsible manner."