* France wants cash deposits, position limits for traders
* Sarkozy demands regulators get clout to punish abuse
* EU's Barroso lends support, Barnier vows trading curbs (Adds Barnier comment)
By John O'Donnell and Charlie Dunmore
BRUSSELS, June 14 (Reuters) - French President Nicolas Sarkozy called for tighter controls on the speculators he blames for spiralling food and energy prices, spelling out reforms to put more trading under the thumb of regulators.
Sarkozy, head of the G20 group of the world's leading economies, said he wants to extend the use of cash deposits to all derivative deals, not just those on formal exchanges as is current practice.
The French president's proposals are designed to rally support throughout the European Union support for a regulatory crackdown on speculating on commodities from oil to grain.
"Following the United States and Europe, all G20 countries should commit themselves to this way forward," said Sarkozy, drawing parallels between regulating against financial speculation and combating the mafia.
If successful, Sarkozy's proposals would widen the international scope for regulating commodities to include both trading of actual raw materials and informal over-the-counter deals which are not recorded centrally, experts said.
"This is a much broader ambit for regulating," said Edmund Parker, a derivatives specialist at law firm Mayer Brown, saying that compulsory cash deposits would make trading more expensive.
Sarkozy also proposed giving regulators the clout to stop market malpractice, allowing them to impose position limits that would cap the size of individual trades.
He added that highly complex derivatives should be standardised, and listed on markets or platforms where they can be closely watched by regulators.
Michel Barnier, Sarkozy's political ally who is in charge of EU regulatory reform at the European Commission, announced later on Tuesday that he would allow watchdogs to impose position limits restricting the size of individual trades.
That would take Brussels closer to Washington but still falls short of the more hard-line approach there which imposes permanent caps on the size of individual trades.
"We must be in a position to know not only the exact state of stocks and demand ... but also the identity of the parties to a given transaction," Sarkozy said.
Speaking at the same event, European Commission President Jose Manuel Barroso lent his support.
"We are touching on a problem which is likely to become vital," said Barroso.
The European Commission will draft the first version of laws to control derivatives markets later this year.
Sarkozy's appearance in Brussels to comment on issues of financial regulation is rare and he will hope it builds momentum for a process of reform which many EU officials fear is flagging.
He has the backing of Germany but will struggle to win support in Britain, home to Europe's top financial centre.
"It's an extremely important signal from France to the Commission," said Karel Lannoo of the Centre for European Policy Studies, a Brussels think tank, adding, however, that the chances for a global deal were far less certain.
Although Sarkozy argued the case for protecting, as he put it, the Ivory Coast peasant producing cocoa, many in London will see his campaign as an attempt to protect French farmers and undermine London, Europe's top centre for trading derivatives.
France is using its G20 presidency this year to try to tackle rising prices for commodities such as grain, which it says have triggered social unrest in North Africa and the Middle East and fuelled inflation elsewhere.
But with countries like Britain opposed to plans allowing watchdogs impose caps on trades, Sarkozy may struggle to build global agreement.
The United States, on the other hand, which has urged the EU and others to follow it in tightening rules on derivatives trading, will be pleased with his tougher line.
His remarks won praise from regulators at the U.S. Commodity Futures Trading Commission, who said the French president had "got it exactly right." (Additional reporting by Huw Jones in London) (Editing by Eric Onstad and Geert De Clercq)