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Brent crude slid below $110 a barrel on Thursday, dragged down by a survey that pointed to slower growth in China, the world's second largest oil consumer.
Manufacturing activity shrank again in February to the lowest in seven months, while employment fell at the fastest pace in five years, a preliminary private survey showed.
"That is going to really knock the wind out of sales of risk assets this afternoon and probably for the next 24 hours because it is a substantial miss on estimates. I expect that it is going to have a negative impact across oil markets," said Ben Le Brun, a market analyst at OptionsXpress in Sydney.
April Brent crude had slipped 60 cents to $109.87 a barrel by 0540 GMT, after settling at its highest level this year on Wednesday.
US crude futures for March delivery edged down 27 cents to $103.04 a barrel. The contract closed on Wednesday, a day ahead of its expiry, at its highest since October 8.
April Brent's premium to WTI has fallen to the lowest since October after a new pipeline diverted excess supply from Cushing, Oklahoma, the WTI contract's delivery point, to the gulf coast. Robust heating demand this winter has also supported US crude prices.
Crude stocks in Cushing fell by 1.8 million barrels in the week to February 14, data from industry group the American Petroleum Institute showed. Traders are waiting for numbers from the US Energy Information Administration later in the session for confirmation.
Geopolitical risks in Africa and Venezuela partially offset the negative impact on oil from the China survey.
Domestic conflicts in Libya and South Sudan have cut their crude output, while investors eyed protests in Venezuela and the progress of Iran's nuclear talks.
Six world powers and Iran hammered out an agenda for reaching an ambitious final settlement to the decade-old standoff over Tehran's nuclear programme. A settlement could lead to the lifting of sanctions on Iran which has been curbing oil exports from the OPEC producer.
Iraq may also add to global oil supply after Iraqi Kurdistan agreed to export crude via the country's main oil marketing body, potentially removing a major sticking point in a resource row with the central government.
