Around 1200 GMT, the US benchmark West Texas Intermediate (WTI) for delivery in April declined 22 cents at USD 32.56 a barrel.
In London, Brent North Sea crude for April advanced 23 cents to USD 35.33 a barrel compared with Friday's close.
Crude futures had risen in earlier Asian trading today, boosted by hopes that strengthening growth in top global consumer the United States will soak up some of the chronic supply glut.
Chief market strategist Michael McCarthy at CMC Markets in Sydney said last week's better-than-expected US growth and manufacturing data signalled stronger demand for oil.
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Oil rallied sharply last week on hopes that top producers will cut output, but McCarthy said traders have "heavily discounted" speculation of a deal between members of the OPEC cartel.
"Amongst traders OPEC has zero credibility, I don't think that as an organisation it factors into thinking of the end users of the market," McCarthy said.
"Traders just have no faith that OPEC has the capacity to do anything."
But Saudi Arabia, OPEC's largest oil producer, has since ruled out a production cut and Iran has dismissed joining a freeze.