Refiles to more subscribers. Corrects SRC's refining capacity in paragraph 4 and ExxonMobil Singapore's refining capacity in paragraph 5.

By Trixie Yap

SINGAPORE, March 10 (Reuters) - A growing number of refineries in Southeast Asia, which are reliant on Middle East oil, have cut back output due to constrained crude availability resulting from the U.S.-Israeli war with Iran, sources told Reuters.

The conflict has effectively halted shipments through the Strait of Hormuz, where a fifth of global oil and liquefied natural gas normally passes along Iran's coast, and producers have run out of storage and stopped pumping.

Malaysia's Pengerang Refining Co (Prefchem), a joint venture between Petronas and Saudi Aramco 2222.SE, shut its 300,000-barrel-per-day crude unit last week and plans to halt more of its derivative units soon due to a lack of crude feedstock, six sources with knowledge of the matter said.

It had been running at 50% capacity, Reuters has reported.

Another processor, Singapore Refining Co $(SRC)$, has cut refinery runs at its 290,000-bpd Jurong Island site in Singapore to around 60%, five other sources said, from what one of them said was 75% previously.

U.S. major ExxonMobil XOM.N has also cut crude runs to around 50% or lower from around 80% or more at its 592,000-bpd Jurong Island refining site, a separate three sources with knowledge of the matter said, due to crude delivery delays from the Middle East.

The refinery in Singapore has this year sourced around 65% of its crude via the Strait of Hormuz, Kpler shiptracking data showed.

Exxon declined to comment on the matter. Export-focused operator Prefchem did not respond to a Reuters request for comment. And SRC did not have immediate comment.

PREFCHEM PLANNING FURTHER SHUTDOWNS

Prefchem is expected to shut its 1.2 million-ton-per-year steam cracker this week, two of the six sources familiar with its plans said, after stopping operations at its 70,000-bpd residual fluid catalytic cracker gasoline-making unit in the past few days.

More than 70% of Prefchem's seaborne crude imports last year came via the Strait of Hormuz, Kpler shiptracking data showed.

Last month, Prefchem shut its other gasoline-making unit for repairs, Reuters reported.

SRC MAINTAINING REDUCED RUNS

For now, SRC is likely to maintain reduced runs until the end of the month, given the delay of delivery of some crude import cargoes this month, said two of the five sources with knowledge of its plans.

SRC has cut or delayed March naphtha deliveries to at least two offtakers, one of the five people, plus two other sources said.

The refinery imported around 179,000 barrels per day of crude via the Strait of Hormuz last year, Kpler data showed, with traders saying it typically imports around 6 million barrels of crude per month in total.

SRC is a 50/50 joint venture between PetroChina's 601857.SS Singapore Petroleum Co Ltd and U.S. major Chevron CVX.N.

Last week, at least two Chinese refineries shut crude units, while several petrochemicals firms in Asia have declared force majeure since the start of the Iran war due to tight supplies of feedstock naphtha.

(Reporting by Trixie Yap; additional reporting Siyi LiuEditing by Tony Munroe and Joe Bavier)

((trixie.yap@thomsonreuters.com;))