Oil prices were mixed in volatile Asian trade today amid concerns that the spread of swine flu could dampen hopes of an economic recovery in the recession-hit US economy.
New York's main futures contract, light sweet crude for June delivery, was down one cent to $50.96 a barrel.
Brent North Sea crude for delivery in June rose one cent to $50.79.
Dave Ernsberger, senior editorial director at energy information provider Platts, said: "the fundamental data from the oil market is fairly supportive now."
He was referring to the larger-than-expected decrease in US gasoline stockpiles released yesterday, indicating stronger demand in the world's biggest economy.
But Ernsberger also warned that signs of an economic recovery risked "being completely derailed by the swine flu."
The World Health Organisation (WHO) raised its flu alert on Wednesday signalling a swine flu pandemic was "imminent."
"All countries should immediately now activate their pandemic preparedness plans," WHO chief Margaret Chan said as she raised the alert to five on a scale of six following WHO health expert talks in Geneva.