"I am delighted with the breakthrough in negotiations over the sale of the Murco oil refinery in Milford Haven," Stephen Crabb, MP for the area in south west Wales where the refinery is located, told the Western Telegraph.

Murphy was unable to provide an immediate response to the report.

The plant is currently not buying crude oil, but recycling oil products to keep it operational.

Murphy started a 45-day consultation period in April with staff and unions, which it has left open since it lapsed in May.

A source told Reuters on Thursday that any deal would likely value the plant at close to zero, but any sum paid for the plant would include oil inventories.

The Klesch Group is a global industrial commodities business, with three divisions specialising in the production and trading of chemicals, metals and oil.

Nobody at Klesch was immediately available to comment on Sunday.

The roughly 500 workers at the plant will be relieved if the deal does go through, as it was widely thought the plant was heading for closure. Refineries in Europe are being squeezed by high crude prices and low refining margins due to weak demand for fuel.

(Reporting by Simon Falush)