Oil prices rose in Asia Wednesday after US President Barack Obama said he was not sure a deal could be reached this week on Iran's disputed nuclear programme.

New York's main contract, West Texas Intermediate (WTI) for December delivery, was up 31 cents at $93.65 while Brent North Sea crude for January added 32 cents to $107.24.

"We may attribute the rise of crude oil to a pent-up risk premium as Iranian nuclear talks resume, with market watchers doubting an ease in sanctions anytime soon," CMC Markets analyst Desmond Chua said in Singapore.

Prices rose despite expectations that an upcoming US Energy Department report will show crude stockpiles gained for the ninth week in a row.

Iran, a major oil producer, has expressed optimism that a deal could be achieved in Geneva with negotiators from the United States, China, Russia, Britain, France and Germany -- known collectively as the P5+1 group.

The talks aim to convince Iran to roll back its nuclear programme, which Tehran is accused of using to build nuclear weapons, a charge it denies. In exchange, they are offering relief from sanctions.

"I think there is every possibility for success," Iranian Foreign Minister Mohammad Javad Zarif said after meeting his Italian counterpart Emma Bonino in Rome on Tuesday.

"I go to Geneva with the determination to come out with an agreement at the end of this round," Zarif said.

But Obama struck a cautious tone, insisting any relief from sanctions -- which include a ban on oil exports -- under an interim pact was limited.

"I don't know if we will be able to able to close a deal this week or next week," he said at a Wall Street Journal CEO forum.

Obama has asked key senators to delay imposing new sanctions on Iran during the negotiations, said White House spokesman Jay Carney.