Geneva ? The record generosity toward tsunami victims, now at more than $4 billion pledged, should set the standard for caring for the world’s most desperate people, the U.N. humanitarian chief said Tuesday. But aid group Oxfam said it feared the money might simply be rerouted from existing funds for Africa.

Jan Egeland, U.N. undersecretary-general for humanitarian affairs, said a new outside auditing system would not only prove a further guard against any misuse of funds given to the United Nations, but will also make sure governments meet their pledges.

“We are seeing an extraordinary effort, probably unique in the history of humankind,” Egeland said after an 81-nation meeting with ministers and other officials.

Both Indonesia and Sri Lanka tried Tuesday to defuse tensions with insurgencies to make sure aid efforts weren’t disrupted on the ground.

Indonesia offered a cease-fire to rebels in Aceh province, the area hardest-hit by the Dec. 26 earthquake and tsunami that killed more than 150,000 people. A rebel spokesman said the offer was a positive step even if it was late in coming.

In a gesture apparently aimed at helping mend the rift between warring communities in Sri Lanka, President Chandrika Kumaratunga — an ethnic Sinhalese — announced plans to adopt a child from the disgruntled Tamil minority orphaned by the tsunami.

So far, governments and international development banks have pledged more than $4 billion to aid 5 million tsunami victims across the region. That figure does not include private contributions.

“We do not yet have the cash in hand required to meet even the most urgent needs,” Egeland said. “We are in a race against time, and we need cash now if we are going to provide assistance to all in need during the next six months.”

Egeland said $717 million had been converted from pledges to binding commitments.

A U.S. Marine helps Sri Lankan children clear rubble out of their school, named Maha Videyalaya, in Gintota, southern Sri Lanka. Governments worldwide have pledged about billion in tsunami aid, but a U.N. official warned Tuesday that it was crucial the pledges be delivered, and soon, to prevent more deaths.

But some donors have failed to make good on their promises after past disasters, and aid groups say they will keep the pressure on to make sure the help recently announced with great fanfare doesn’t evaporate.

For example, donors promised more than $1 billion after an earthquake killed 26,000 people in Bam, Iran, in December 2003. A year later Iran says it’s gotten only $17.5 million.

Even if all the pledges are honored, Oxfam said it fears money earmarked for African relief may be shifted to Asia and urged countries to confirm that their donations would be “new” money, not taken from another aid project.

“At the moment we’re looking at Germany, who have confirmed that all of the money that they’re pledging is new money,” Oxfam spokeswoman Amy Barry said. “Nobody else has done that so far.”