Refineries across Asia plan to cut production in September by more than 700,000 barrels per day (bpd), various refinery sources said on Monday and Tuesday.

That has prompted market worries that the refiners will back out crude that they had previously bought in order to sell it into the spot market.

"We have received calls from some refiners who have plans to back out their crudes, but nothing firmer than that," a trader in Tokyo said, who declined to disclose the identities of the refiners.

Market speculation was rife that Singapore's Shell may back out a 400,000-500,000 barrel cargo of Middle East crude for October delivery. Sources at the refinery could not be reached for comment immediately.

Traders said most refiners were also rather hesitant to offer their crude cargoes into the spot market forfear it would exacerbate the bearish trend.

"If these cargoes are out in the market, the pressure on prices would be even greater," a trader said. "As it is, we can't see anybody so eager to buy at this point in time."

The announcements of refinery cutbacks in Singapore, South Korea and Thailand only served to aggravate an already bearish mood, traders said.

Traders said overall consumption was undeniably weak.

"I don't see it (the cutbacks) having a big, positive impact on crudes. With the fundamentals looking weak, what the market needs now is some real demand to pull it up," a trader with a European refiner said.

Traders estimated that about 15 cargoes of Abu Dhabi crude and 10 cargoes of Oman -- all for October loading -- have yet to find buyers and there was little sign that any firm buying interest would emerge shortly.

Time is already running out for the October market. November barrels would start being marketed by the middle of this month.

On Monday, Singapore's Shell refinery said itwould cut runs at its 435,000-barrels-per-day refinery to slightly less than half capacity in September.

South Korea's SK Corp, with a refining capacity of 865,000-bpd, would also cut output in September to 650,000 bpd and in October to 700,000 bpd, a company source said.

Petron Corp in the Philippines is maintaining a modest cut and some refineries in Thailand have cut production.

Japanese refiners, on the other hand, said on Tuesday they planned to reduce crude throughput in the October-December quarter, but the magnitude of the cuts would be much smaller than those of their Singapore and South Korean counterparts.