The refinery, which now processes about 275,000 barrels a day, will be completely offline by mid-July, spokesman Bill Day said Monday in an email.

The San Antonio, Texas-based refiner will decide whether to restart operations in August or September.

The plant's 700 workers will meanwhile perform routine maintenance projects or join training programmes during the shutdown, he added.

A spokesman for the Independent Oil Workers Union of Aruba, which represents most of the plant's employees, did not return a call for comment on Monday.

Valero, the largest refining company in the United States, bought the Aruba plant in 2004 but has been looking to sell it since last year.

Day said Monday that no date had been set for a sale. He declined to provide further details and named no prospective buyers.

The facility processes heavy crude into distillate products that are shipped to US refineries to be made into lighter fuels, including gasolene.

- AP