Brent futures fell more than a dollar to a one-week low below $113 on Monday, with supply disruption worries receding as a military strike against Syria looked less imminent.

Fears eased after US President Barack Obama said he would seek congressional authorisation for punitive military action against Syria. That would likely delay any strike at least nine days as the current summer recess ends on September 9.

Losses were stemmed as a surprise improvement in China's factory activity stoked hopes of a revival in demand growth.

Brent futures fell as low as $112.20 a barrel and were trading down $1 at $113.01 by 0347 GMT. Losses in the US benchmark were steeper. It declined to a low of $104.21, and was down $1.47 at $106.18.

"Oil would have been pushed lower had it not been for the China data we saw over the weekend," said Ben Le Brun, a market analyst at OptionsXpress in Sydney said. "The market is keeping an eye on the Middle East and developments in Syria, but we have seen some tensions easing and prices are coming off."

Brent rose nearly 3 per cent last week, the biggest weekly gain since early July, on worries that a strike by Western forces against Syria would rattle the Middle East and disrupt oil exports when markets are already coping with the loss of supplies from Libya and Sudan.

Before Obama announced his plans of seeking approval from Congress, the path had been cleared for a US assault. Warships were in place and awaiting orders, and UN inspectors had left Syria after gathering evidence on the use of chemical weapons.

The United States had originally been expected to lead a strike relatively quickly, backed by Britain and France. But British lawmakers voted last week against involvement, and France said on Sunday it would await the US Congress decision.

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"I would be surprised if there is no action taken against Syria," said Le Brun. "The market is watching if the strike will just involve Syria, or will its neighbours, who are major exporters of oil, join in."

Without further escalation, Le Brun expects the US benchmark to trade around $106 a barrel and Brent around $113. If there is a heightening of tensions, prices could see a $3-$4 a barrel spike, he said.

China's factory activity expanded at its fastest in more than a year in August with a jump in new orders in the world's second-biggest oil consumer, official data showed on Sunday.

In another sign that China may have averted a sharp slowdown in its economy, a separate private survey showed China's factory activity expanded for the first time in four months in August as domestic demand rebounded.

A fall in supplies from the producer group the Organisation of the Petroleum Exporting Countries (Opec) also helped put a floor under prices. Opec supply averaged 30.32 million bpd (bpd) in August, down from a revised 30.50 million bpd in July. - Reuters