SINGAPORE, April 27 (Reuters) - Northeast Asian spot diesel and jet fuel exports are set to show a recovery in May as refiners capitalise on record margins and improving crude oil supply, trade sources said.

Reuters data showed refiners in South Korea and Taiwan have sold more diesel and jet fuel cargoes loading in May than April although the volume remained below pre-Iran war levels.

Refining margins in Asia soared to all-time highs of about $60 a barrel earlier this month.

The rise in exports has helped ease record spot premiums of both diesel and jet fuel in the Asia Pacific which strained countries as the conflict cut most of the region's oil supply through the Strait of Hormuz. 

South Korea's SK Energy, GS Caltex, S-Oil and Hyundai Oilbank sold a total of more than 10 diesel cargoes loading next month, more than twice April's volume, Reuters data shows. [MDIS/TENDA] 

Meanwhile, Taiwan's Formosa Petrochemical Corp sold one cargo each of 10 ppm sulphur and 500 ppm sulphur diesel cargoes for May, the data showed, compared with none for April. 

Each cargo is around 300,000 barrels. 

These sale volumes, however, are still lower than pre-conflict levels of 25 cargoes or more. 

For jet fuel, these refiners have sold at least five 300,000-barrel cargoes for May, compared with around three cargoes for April, two trade sources said.

RISE IN SUPPLY EASES PRICES

Although spot premiums and refining margins have eased with the recovery in fuel exports, they are still many times the levels seen before war began on February 28, indicating that supply is limited as refineries across Asia and the Middle East grappled with lower output.

These diesel cargoes loading in northeast Asia were traded at premiums below $5 a barrel to Singapore quotes on a free on board Korea basis last week, down from $10 or more two weeks ago, Reuters tender records showed.

Asian refiners' margins for producing the transport and industrial fuel stood at nearly $62 a barrel on Monday, down from a record of $86 on March 30, but triple that of end-February, LSEG data showed.

Similarly, jet fuel cracks at around $69 a barrel remained more than three times end-February's level, although they have eased from a peak of $94 on March 30.

Cash premiums for aviation and heating fuel have slid to about $18 a barrel, down from their peaks of more than $40 a barrel, but remained more than double that of end-February. 

(Reporting by Trixie Yap; Editing by Florence Tan and Alexander Smith)

By Trixie Yap