Oil prices rebounded Thursday on bargain hunting following sharp falls the previous day, but analysts said markets would continue to be weighed down by signs of weaker demand for crude.
Brent North Sea crude for delivery in June rose 75 cents to $100.70 a barrel approaching midday in London.
New York's main contract, light sweet crude for June was up 37 cents to $91.40 a barrel.
Both contracts had closed down by more than $2.40 Wednesday on fresh signs of economic weakness in the United States and China -- the world's largest crude consumers.
A US oil inventory report on Wednesday showed crude stocks increasing by 6.7 million barrels for the week ending April 26, far above the 800,000-barrel forecast by analysts.
This brought inventory stocks to a 395.3-million total, the highest weekly figure since the US Energy Information Administration began collecting the data in 1982.
A rise in inventory stocks indicates weak energy demand and puts a downward pressure on prices.
Separate data has showed a slowdown for US and Chinese manufacturing activity.
Ric Spooner, chief market analyst at CMC Markets in Sydney, said the oil market remains concerned over "a picture being painted of moderate demand and fast-building inventories of crude supply".