North Sea Brent crude oil futures were lower for a fifth day on Tuesday, trading at a nine-month low below $100 a barrel.

U.S. benchmark crude, down for a fourth day, was at its lowest level so far in 2013, as the market remained under pressure from signs of weak oil demand growth.

Forecasters sounded the warning last week that global demand wouldn’t gain as much as expected, sending prices tumbling. Weaker-than-expected growth in China–the world’s second-biggest oil consumer and the engine of growth for oil demand–reported Monday spurred furious selling.