Brent futures slipped towards $114 a barrel on Monday, falling for a second session due to worries over weak oil demand, although concerns over potential supply risks from tension in the Middle East kept losses in check.
China's crude oil imports rose in September, but demand remained weak, underlining a worsening outlook for global fuel consumption.
Prices were also hurt as the International Energy Agency (IEA) last week cut its demand growth forecast for next year.
Brent crude had slipped 9 cents to $114.53 a barrel by 0930 GMT, after sliding 75 cents in the previous session. U.S. oil was down 25 cents $91.61 after falling more than a dollar to $90.82 earlier in the session.
China's crude oil imports in September were 12.8 percent higher on a daily basis than the 22-month low of 4.33 million bpd in August, data over the weekend showed.
But the improvement failed to lift hopes that demand in the world's second largest oil consumer was on track for a full recovery, as refineries in China continue to undergo maintenance.
"China's crude oil demand is not as dynamic as it was a few months ago," said Carsten Fritsch, oil analyst at Commerzbank.
"We shouldn't forget that August was an extremely weak month and the imports we saw in September for crude were still significantly beneath what we saw in the first half of the year," he said.
China has set its 2013 non-state crude oil import quota at 29.1 million tonnes, the same as this year, the Ministry of Commerce said on Monday.
The IEA said ample supply from North America and Iraq, coupled with declining global demand, could ease prices over the next five years.
It also cut its demand growth projection for 2011-2016 by 500,000 barrels per day (bpd) from its previous report and cut its 2013 demand outlook by 100,000 bpd, citing lower consumption in Europe, the Americas and China.
But increased tension between Turkey and Syria put the brakes on declining prices and threatened to add to a geopolitical crisis over concerns about Iran's disputed nuclear programme.
Turkey banned all Syrian aircraft from its air space at the weekend, the latest development in a two-week confrontation between the two countries that escalated when Ankara grounded a Syrian airliner.
"Oil markets should continue to swing between tight supply concerns and slowing global demand this week," analysts at ANZ said in a note. "Crude prices are expected to move lower this week unless Middle East tensions escalate." (Additional reporting by Manash Goswami and Manolo Serapio Jr.; editing by Keiron Henderson)