SOUTH Africa has committed $2bn to an International Monetary Fund (IMF) "firewall" meant to prevent future financial crises, the Treasury said on Tuesday.

President Jacob Zuma committed some of South Africa's reserves at the Group of 20 (G-20) summit, a meeting of the world's greatest economies, in Los Cabos, Mexico, spokesman Jabulani Sikhakhane said.

"The funds used for this purpose would be considered part of South Africa's foreign reserves," he said.

"They will be drawn down only if they are needed and only after other resources have been depleted. The funds will be invested and earn interest."

Participating countries with no way out of a financial crisis would access the so-called firewall fund through a temporary loan, with conditions, and not purchase agreements to the IMF's general resources account.

Mr Sikhakhane said the commitment of funds was on the premise that South Africa's voting power and quota shares in the IMF were reformed, as agreed to in 2010. The long-delayed reforms would give the developing world more say at the Washington-based fund.

Presidency spokesman Mac Maharaj, speaking from Mexico, said Brazil, Russia, India, China and South Africa (Brics) were set to release a joint statement shortly stating their expectations.

China had committed to $43bn while Brazil, India and Russia had offered $10bn each.

At the G-20 summit in Cannes last year, world leaders agreed to increase the resources of the IMF as a backstop in the event of further deterioration in the euro-zone situation.

It was hoped the emergency reserves would stave off the risk of another financial crisis, which would likely lead to a sharp decrease in global growth and rising unemployment.

G-20 countries and other IMF members agreed in April this year to commit about $430bn to the special fund, which would be available to all IMF members and not earmarked for a certain region.