Iranian President Mahmoud Ahmadinejad has suggested an end to the trading of oil in US dollars, calling the currency "a worthless piece of paper", BBC reported.
The call came at the end of a rare Opec summit, and was opposed by US ally Saudi Arabia.
The summit in Saudi Arabia was only Opec's third in 47 years.
Speaking after the end of the summit, Ahmadinejad said all leaders at the meeting were unhappy with recent falls in the value of the dollar.
Ahmadinejad said that all Opec countries had showed interest in converting their cash reserves into other currencies.
"They [the US] get our oil and give us a worthless piece of paper," he told reporters.
The Iranian president had wanted to include the attack on the dollar in the summit's closing statement.
The communique made little mention of the dollar, however, focusing instead on energy security and the environment.