But a big drop in U.S. gasoline stocks has offset the impact of the release of 15 British sailors and marines.
Oil prices rose on Thursday, drawing support from a big drop in U.S. gasoline stocks that offset the impact of oil producer Iran's release of 15 British sailors and marines.
U.S. light crude for May delivery was 24 cents higher at $64.62 a barrel by 0843 GMT, while London Brent crude was up 45 cents at $68.85.
Brent has reached a record premium of more than $4 a barrel to U.S. crude, reflecting bigger U.S. supplies.
The capture of 15 British military personnel had pushed U.S. crude to a six-month high of $68.09 last week and prices are still around $3 higher than before the Britons were seized on March 23.
Iranian President Mahmoud Ahmadinejad told a news conference on Wednesday he had decided to forgive and free the captives and they left Tehran on a flight to London on Thursday.
A steep drop in U.S. gasoline inventories has reduced the market impact of their release.
"The gasoline situation tightened considerably and that limited the downside. Stocks are extremely tight," said Gerard Burg, an analyst from National Australia Bank.
Gasoline stockpiles in the world's largest energy consumer fell by five million barrels, data from the U.S. Energy Information Administration showed on Wednesday.
The draw included a decline of two million to three million barrels from the previous week, but still alarmed traders in the run-up to the peak summer driving season.
Gasoline stocks have fallen to the lower half of the historical range, partly as a result of refinery outages, which help to explain high levels of U.S. unrefined crude.
Crude oil inventories rose by 4.3 million barrels, much more than expected.
Traders said oil markets had drawn some strength from other commodity markets.
Copper reached a five-month high on Wednesday and nickel on the London Metal Exchange reached a record of $50,000 a tonne on Thursday, driven by low stocks and strong demand.