The United States and Iran are engaged in indirect talks to develop a framework for a possible agreement, according to Iran's ISNA News Agency.
An Iranian official said negotiators are 'very close' to reaching an understanding, but intensive mediation efforts are still underway.
Oil prices rose as investors doubted a breakthrough in US-Iran peace talks, with the two sides at loggerheads on Tehran's uranium stockpile and controls on the Strait of Hormuz.
A senior Iranian source told Reuters that gaps have narrowed, while US Secretary of State Marco Rubio said there have been 'some good signs' in talks.
