Oil prices rose towards $69 a barrel on Tuesday, underpinned by comments by delegates from an Opec meeting starting tomorrow that is expected to keep output targets unchanged.
Most analysts are expecting producer group Opec to maintain its official output target at about $70, according to Reuters.
"The market is looking for reasons to sell oil, and after the Opec meeting might be a decent excuse. People are worried by under-compliance, the disappointing US driving season, anaemic demand and high stock levels," ANZ's senior commodities analyst Mark Pervan told Reuters.
NYMEX crude for October delivery stood at $68.66 a barrel by 06.35 GMT, up $0.64 from Friday's close. There was no settlement price on Monday because NYMEX was closed for the US Labor Day holiday.
London Brent crude rose $0.77 to $67.30 a barrel.
Crude prices, although up 50% so far this year, are still less than half their peak struck in July 2008.