Oil prices fell in Asian trade today due to sluggish energy demand in the recession-hit United States, analysts said.
New York's main futures contract, light sweet crude for April delivery, fell 82 cents to $49.51 a barrel.
Brent North Sea crude for May delivery tumbled 80 cents to $52.55 a barrel.
Traders said the market was taking notice of a large build-up in US energy stockpiles, which suggests that demand remains weak in the world's biggest economy.
Today's fall in prices is "probably a delayed reaction to the inventory data that came out last week, which was really, really bearish," said Tony Nunan, a risk management manager at Mitsubishi Corp in Tokyo.
The US Department of Energy (DoE) said last Wednesday that crude stocks surged 5.6 million barrels in the week ending April 10 to reach 366.7 million barrels -- the highest level since September 1990.
"Fundamentally we have a demand problem in the world, including the United States," said BMO Capital Markets analyst Bart Melek.
"This overhang of supply is going to be with us for some time."