At about 1100 GMT US benchmark West Texas Intermediate for March delivery was down $1.03 at $30.42 a barrel.
Brent North Sea crude for March shed 66 cents to $31.14 compared with Tuesday's close.
The US Department of Energy publishes its weekly inventory of commercial crude stockpiles on Wednesday -- data that could add to persistent concerns about an oversupply of world oil.
The market was awaiting also the outcome of a meeting of the Federal Reserve on the timing of another rise in US interest rates.
Oil had soared late last week from 12-year lows on hopes of fresh economic stimulus by the European and Japanese central banks.
However, continuing worries about a supply glut, weak demand and the slowing global economy returned to the fore.
Oil rallied again Tuesday though on talk of possible coordination between OPEC kingpin Saudi Arabia and non-OPEC crude producer Russia to cut petroleum output.
That followed remarks Monday from OPEC secretary general Abdullah el-Badri calling on producers within and outside the cartel to work together to boost prices.
The world remains awash with oil supplies, a situation that has been fuelled by OPEC's refusal to curb crude output to squeeze out US shale producers.
The Saudi-backed strategy is aimed also at pressuring Russia -- the biggest global oil producer -- and force fellow OPEC member Iran to trim output.
Prices have suffered a rapid descent this month -- building on a slump stretching back to mid-2014 -- on snowballing concerns over the strong dollar and weak crude demand growth across the faltering world economy -- particularly in top energy user China.