Oil prices have risen to an 11-month high above $76 a barrel as rising global oil demand and North Sea field maintenance increases worries about supply.
London Brent crude, currently seen as a better indicator of the global market, climbed to a high of $76.34 a barrel, the highest level since August 2006. The all-time record high for Brent is $78.65, reached on August 8 2006.
Analysts said kidnappings in Nigeria, the upcoming hurricane season and OPEC's withholding of oil from the market were all adding to uncertainty.
Late this afternoon, Brent crude was 38 cents higher at $76 a barrel. US crude fell 44 cents to $72.37.
The International Energy Agency, adviser to 26 industrialised countries, earlier said world oil demand would rise faster than expected to 2012 while supply would fail to keep up.
'Despite four years of high oil prices, this report sees increasing market tightness beyond 2010,' the IEA said in its medium-term oil market report.
But OPEC ministers disagree, saying refinery bottlenecks and political tensions are to blame for high oil prices this year, not supply shortages.
Expectations that summer maintenance will reduce supplies of crude from North Sea oilfields have also helped boost prices, widening Brent crude's premium to the US grade.
Two North Sea oil platforms linked to the key Forties crude stream will undergo scheduled maintenance for 16 days in August.
