Refiners across Asia are cranking up output to send fuel to the United States, where fallout from Hurricane Harvey has seen around a quarter of the country's refineries shut down.

The storm, which hit Texas a week ago as a hurricane and moved on to Louisiana, has caused historic floods and forced the closure of about a quarter of US refining capacity, equal to about 4.5 million barrels per day in output.

The resulting supply crunch has caused prices to spike - in petrol, diesel, jet fuel and other fuels - and not just in the US.

Attracted by soaring refining margins, known as crack spreads in the industry, Asian fuel makers from Singapore to South Korea have ramped up their operating rates to sell as much cargo as possible to the US.

"With crack spreads blowing out, the US is going to need products ... so Asian and other refiners are going to have to ramp up runs," said Mr Tony Nunan, oil risk manager at Mitsubishi Corp in Tokyo.

Most refiners in Asia have a policy of not commenting on operations, but refinery sources across the region said their plants were maximising runs to reap profits from higher fuel prices and to sell to the US.

"Everybody is looking for cargoes. It's a good money-making opportunity, so we will sell whatever we have after leaving sufficient supplies to meet domestic demand," said an official at Taiwan's CPC Corp.

Sources at Singapore Refining Company said they were sending spare cargo to the US, while a source from a refiner in Thailand said its plant is maximising output in response to the jump in refining margins.

"It's a great opportunity to sell fuel that has sat in storage during the last few years of oversupply," said one trader with another refinery in Singapore.

Analysts say fuel prices will remain elevated for some time as damaged American refineries are repaired and fuel shipments cross from Europe and Asia to the US.

Goldman Sachs said earlier this week that many American refineries could take months to repair flood damage and become operational again.

"The price (for fuels) will continue to be supported until flows are reinstated or imports from Europe and elsewhere pick up," said head of commodity strategy Ole Hansen at Denmark's Saxo Bank.

Shares prices for several major Asian refiners, such as SK Innovation and fellow South Korean S-Oil Corp, have climbed to six-year highs this week as higher margins boosted profit potential.

Thailand's Thai Oil climbed to its highest in nearly 10 years, while Taiwan's Formosa Petrochemical also rallied.

REUTERS