G20 finance ministers promised rescue money for troubled emerging market economies on Saturday and said they would use their full fiscal and monetary firepower to combat the worst downturn since the 1930s.

We are committed to deliver the scale of sustained effort necessary to restore growth, the ministers said in a statement promising extra money for the International Monetary Fund and regional lenders such as the Asian Development Bank.

No figure was published but one official attending the talks told Reuters they centered on more than doubling the money at the IMF's disposal to help countries hit by a halt to credit and investment.

Separately, Gordon Brown, who hosts a G20 summit on April 2, said massive change was about to take place in financial market regulation, notably supervision of hedge funds and other areas currently only lightly regulated.

The statement issued by the ministers after their talks to prepare that summit said hedge funds should be registered and disclose information needed to keep tabs on risk, and it said credit ratings agencies should be better controlled too.

It said the top priority now was to get lending, lifeblood of the economy, flowing normally again.

The ministers set aside differences on the scale of public spending deployed to support activity, saying everyone would do all they can to fight what the IMF calls the Great Recession.

The United States has yet to detail how it plans to clean up banks' toxic assets, which many say is vital to get a sclerotic economy moving again, though a U.S. official said details could be expected in the coming week.

The G20 issued a separate set of guidelines for countries to use in planning to rid banks of rotten assets.

You're going to see us announce relatively quickly a new framework, a new financing framework, for these legacy assets, U.S. Treasury Secretary Timothy Geithner, who was at the talks in Horsham, south of London, told Fox Business News.

RENEWED DRIVE?

Washington is also preparing to show its hand later this month on regulation of the financial markets, where G20 leaders have yet to put flesh on promises to bridle excess and ensure that everyone has to be called to account from now on.

President Barack Obama sought to stamp out any doubts about U.S. commitment, telling a Washington news conference nobody would pursue regulation more vigorously than him.

Beyond demanding registration of hedge funds and closer tabs on credit rating agencies, the newer element from the G20 talks in England was the commitment to help for emerging economies, perhaps mindful of the mass exodus of money that marked the Asian financial crisis of the 1990s.

We really must take action to stop damage being done to the emerging economies, who are seeing money coming out of their systems, said British Finance Minister Alistair Darling, who hosted the gathering at a luxury countryside hotel in Horsham.

The IMF has pledged nearly $50 billion for bailing out countries in eastern Europe in recent months and is asking for its rescue funding to be doubled to $500 billion.

The G20 accounts for over 80 percent of the world's output, or gross domestic product, which is expected to shrink in 2009 by more than any year since the 1930s after the financial crisis that erupted in the United States in 2007 engulfed confidence, activity, trade and jobs worldwide.

The United States was demanding earlier this week that other governments commit two percent of GDP to extra spending to stimulate growth, and more than some are currently doing, but that exposed a rift with the likes of Germany and France who say they are doing enough.

World Bank chief Robert Zoellick, also attending the meeting on Saturday, said government spending would give the economy no more than a brief sugar high if governments failed to rid banks of toxic assets that continue to undermine confidence, trust and the desire to lend or invest.

There is this commitment, which is absolutely critical, that the 20 largest economies in the world stand ready to do whatever is necessary for as long as is necessary, and I think that is a major step forward, Darling said.

(Reporting by Reuters G20 team and bureaus worldwide; Writing by Brian Love; Editing by Ruth Pitchford)