New York's main contract, West Texas Intermediate (WTI) crude for delivery in May was up three cents to $US102.96 per barrel while Brent North Sea crude for June shed 38 cents to $US118.30.
"Investors are seeing the Iran talks over the weekend as fairly positive and that is putting downside pressure on Brent crude currently," said Nick Trevethan, senior commodities strategist at ANZ Research.
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WTI was supported by stronger-than-expected retail sales data in the United States, he added.
US Commerce Department data released on Monday showed a 0.8 per cent expansion in overall retail and food service sales in March, pointing towards rising demand in the world's largest economy.
Despite a month-to-month slowdown compared to February, the pace of growth was solid and marked a 6.5 per cent increase from March 2011.
The earlier start date of the Seaway pipeline reversal that will ease a supply glut at Cushing, Oklahoma - the delivery point for US crude - was also supporting prices, Trevethan said.
A spokesman for the project on Monday announced that the pipeline will begin delivering crude ahead of schedule in May, Dow Jones Newswires reported.
Meanwhile, talks between crude producer Iran and delegates from six major powers about Tehran's nuclear programme have allayed investors' jitters about a possible conflict in the Middle East that could disrupt supply.
Tehran has been slapped with several rounds of financial sanctions as part of an international effort to persuade it to abandon its uranium enrichment activities, which is purported to be geared towards building atomic weapons.
Tehran has insisted that its nuclear programme is for peaceful civilian purposes.