"The dollar is falling, all heads of state were upset today because of the dollar. The value of their [financial] reserves has dropped," Ahmadinijad told a press conference. "All leaders taking part in the meeting were willing to convert the pricing of oil into a currency other than the dollar," he said.

"The meeting decided to direct our ministers of finance and oil to talk about this and later produce their findings," he said.

Ahmadinijad also said that Iran proposed that OPEC should have its own strong currency because that would serve the interests of all world countries, besides OPEC.

Iran, the second largest OPEC oil producer, has already moved away from collecting payment for its oil in dollars and instead is paid in local currency from customers.

But benchmark prices for crude are priced in the US currency, which has declined sharply in value against other currencies recently, reducing the oil revenues of oil exporters.

A final declaration issued at the end of the two-day OPEC summit Sunday however failed to make an explicit reference to the weak dollar.

The OPEC statement said simply that the cartel would "study ways to increase financial cooperation between OPEC member countries, including a proposal by some heads of state" without giving more details.

"It is great that the finance ministers will study the subject more ... and get a consensus," oil minister Gholam Hossein Nozari told reporters.

Iran had pushed for OPEC to take collective action to price oil in other currencies such as the Euro, instead of the US currency, which is used across the world at present. But moderate Saudi Arabia, a key US regional ally, objected saying this could cause the dollar to collapse.

The fall of the dollar, which has weakened considerably against the Euro and other currencies in the past 12 months, has affected the revenues of OPEC members because most of them price and sell their oil exports in the US currency.

The issue is also political, with US arch-foe Iran keen to undermine the US currency.