* OPEC backs dollar oil trade
* Tradition of dollar hard to overturn and would take years
By Tom Bergin and Alex Lawler
LONDON, Oct 20 (Reuters) - Oil producers and executives on Tuesday said the dollar was likely to stay the currency of oil trade and dismissed persistent speculation of a possible switch.
A deep-seated debate over commodity dealings was rekindled by a British newspaper article earlier this month that said China, Japan, Russia and France were in secret talks with Gulf Arab states to stop using the U.S. dollar for oil trading.
Big oil producers denied it at the time, but the dollar's slide to 14-month lows against a basket of currencies has kept the question of whether it can remain the world's reserve currency on the agenda and stoked speculation the report of a commodity trading switch could have some foundation.
OPEC Secretary General Abdullah al-Badri said he knew of no plans for a change.
"No, no," Badri told reporters on the sidelines of an industry conference in London.
The euro, he said, would be the only currency that could be used and even then any transition would be long.
He cited by way of precedent the move from sterling to the dollar as the world's reserve currency that only happened after two world wars.
Many oil producers have a vested interest in the U.S. currency as they have huge dollar holdings and close ties with the United States, although U.S. foes, such as Iraq under the regime of Saddam Hussein, have taken some oil payments in euros.
REAL SHIFT VERY HARD
Settling particular contracts in a currency other than the dollar is easily achieved, but shifting away from dollar-pricing for commodities would require a huge effort to overturn years of established practice.
Oil executives in London saw no appetite for it.
"I don't think that oil will be moving from dollars to euros," Paolo Scaroni, chief executive of Italian oil major ENI , told Reuters Television.
"Tradition is very important. We are all used to the dollar and it would be very difficult to shift to a basket of currencies."
The report earlier this month in the Independent newspaper said talks were focused on switching over a nine-year period to a basket of currencies, including the Japanese yen and Chinese yuan, the euro, gold and a new unified currency planned for nations in the Gulf Co-operation Council.
Jim Mulva, chief executive of ConocoPhillips, took a similar view to Scaroni.
"I think oil will continue to trade to a great extent, certainly, in dollars," Mulva told Reuters in an interview on Tuesday.
Whether the world trades oil in dollars or not is of huge significance to the U.S. economy, as well as to other governments that might think it is their turn to acquire the advantage the United States has long held.
But from a pragmatic trading point of view, it makes no difference.
For Christof Ruehl, chief economist at oil major BP the only criterion is that the currency of oil trade is convertible.
"Whether you pay in Japanese yen or in dollars or in BMWs doesn't make a difference," he told Reuters Television.
Ashok Shah, chief investment officer at London and Capital, said alternative currencies could not yet emulate the dollar.
"It's only an option when the Chinese and others actually let their currencies become more liberalised, until that is accepted the alternative is not on the table. You can talk about it but it's not on the table," he said. (Additional reporting by Veronica Brown and Jane Grieve; writing by Barbara Lewis; editing by James Jukwey)