Dubai and Oman prices jumped by more than $1, in line with Brent and US crude, after the United States approved air strikes against Islamist militants in Iraq, raising concerns over the security of oil supplies from OPEC's second largest producer.
But DME Oman's premium to Dubai was little changed in the subdued market on expectations of ample supply as the arbitrage window for oil from other regions such as West Africa and Latin America was open.
Refiners are assessing their demand for October-loading cargoes while waiting for the release of more monthly prices from Kuwait, Iran and Iraq.
Traders eyed Basra Light's OSP, wondering if Iraq will make a more aggressive price cut than Saudi Arabia after Asian buyers avoid purchasing the Iraqi grade due to geopolitical risk.
A rise in the number of cargoes of North Sea Forties available for loading in September combined with a weak Brent versus Dubai have prompted talks of the European grade being sold to South Korea, traders said.
The supply of North Sea crude that underpins the Brent benchmark will rise in September to an average of 880,000 barrels per day (bpd), loading schedules provided by trade sources showed on Thursday. The Forties crude stream will load 17 cargoes in September, up from a revised seven in August.