Oil prices rose in European trading, aided by a surprise fall in US stocks, according to an industry estimate, but gains were capped ahead of the release of official data later Wednesday.
At 1010 GMT, the price of a barrel of Brent crude for November delivery was $48.54 on London's Intercontinental Exchange (ICE), a gain of 79 cents from Tuesday.
In electronic trading on the New York Mercantile Exchange (Nymex), a barrel of WTI crude for delivery in October rose 83 cents to $45.42.
The rise in the price of Brent was primarily due to technical factors, analysts noted.
However, prices were also supported by the industry group American Petroleum Institute finding a drop in US stocks on Tuesday.
"The American Petroleum Institute reported yesterday evening that stocks had decreased by 3.1 million barrels week-on-week in the week to 11 September," noted analysts at Commerzbank.
"The market had been anticipating an inventory build, as refineries scale back their processing during the usual autumn maintenance period, with the result that crude oil stocks generally rise," they added.
The market was waiting for the US Department of Energy to publish its official figures later on Wednesday to gauge demand in the world's top oil consuming nation.
A poll of experts by Bloomberg News showed the consensus estimate is for a gain of 2 million barrels in the week to September 11. A build in the inventories reflect softer demand.
Traders' attention is also focused on a decision Thursday of the US Federal Reserve on the timing for an interest rate increase.
Some analysts are expecting a rate hike to come this month while others are predicting it to happen in December.
"Opinion is really mixed," said Daniel Ang, an investment analyst with Phillip Futures in Singapore.
"We're seeing the market split on this. At the end of the day we will only know about the results later this week so there's a lot of speculation at the moment."
Interest is keen in the oil market on a Fed decision because a raise in the benchmark federal funds rate from zero, where it has been pegged since 2008, could boost the greenback, making dollar-priced crude oil more expensive in other currencies and possibly weighing on demand and prices.