Brent crude fell below $99 per barrel weighed by the prospect of sluggish fuel demand in top consumers in the United States and China and in addition to rising stockpiles of U.S. crude.
More bleak economic news came courtesy of the International Monetary Fund (IMF), which trimmed projections for this year and next - implying limited upside for oil demand growth.
The North Sea benchmark has lost nearly 6 percent over the past five sessions in a wider commodities rout triggered by data showing growth in China, the world's second largest oil burner, had slowed unexpectedly in the first three months of 2013.
The head of the International Energy Agency, Maria van der Hoeven, said the oil price decline was proof that the market was adequately supplied.
Brent crude shed $1 to $98.91 after sinking earlier to $98.80, the weakest since July 2012. U.S. crude slipped $1.29 to $88.43.