Oil prices climbed further above $68 today as traders eyed possible further disruptions to Nigerian oil output after election results condemned by international observers.
London Brent crude, seen as more representative of global oil prices than US crude, rose 30 cents to $68.45 earlier, after jumping $1.66 yesterday.
US crude was up seven cents at $65.96.
Nigeria's ruling party candidate Umaru Yar' Adua was declared the winner of a presidential poll, but observers and opposition groups said the result was manipulated through violence and rigging.
Analysts raised concerns over the potential for more violence against the oil industry, which has already curbed about 20 per cent of the Opec nation's total output.
Analysts said oil prices were also getting a boost from petrol supply concerns in the United States ahead of the summer driving season when demand peaks, with US oil product futures rallying yesterday.
Petrol stocks are expected to see a small draw in data due tomorrow, the 11th week that stocks have fallen, a preliminary poll of industry analysts showed yesterday.