New York's main contract, West Texas Intermediate crude for delivery in September, fell 45 cents to USD 87.43 a barrel in morning trade. Brent North Sea crude for September was down 42 cents to USD 109.49.
"Investors will be waiting for details on the eurozone meeting and the eurozone second-quarter GDP figures," said Ker Chung Yang, an analyst at Phillip Futures in Singapore.
French President Nicolas Sarkozy will host German Chancellor Angela Merkel yesterday in Paris to produce a road map for the 17-nation eurozone as it battles its growing sovereign debt crisis.
Merkel and Sarkozy lead the eurozone's two biggest economies and markets have been watching anxiously to see whether they will agree a plan to boost fragile confidence.
The finance ministers of Britain, Australia, Canada, Singapore and South Africa on Monday said in a statement that the world was facing a crisis of confidence and needed a global response.
The ministers warned of a lack of confidence in efforts by governments to address the issues underpinning weak growth, high unemployment and unsustainable fiscal balance sheets.
Trillions of dollars have been wiped off stock markets in a massive sell-off over the past fortnight as investors dumped shares over concerns of a global slowdown, eurozone debt, and an unprecedented US credit rating downgrade.
The fears for the global economy have triggered volatility for oil prices in turn, as traders anticipate a deterioration in energy demand.