The public's reluctance to contribute much more than the cost of two iPods to the administration's attempt to offer citizens 'a further stake in building a free and prosperous Iraq' has been seized on by critics as evidence of growing ambivalence over that country.

This coincides with concern over the increasing cost of the war. More than $30 billion has been appropriated for the reconstruction. Initially, America's overseas aid agency, USaid, expected it to cost taxpayers no more than $1.7bn, but it is now asking the public if they want to contribute even more.

It is understood to be the first time that a US government has made an appeal to taxpayers for foreign aid money. Contributors have no way of knowing who will receive their donations or even where they may go, after officials said details had be kept secret for security reasons.

USaid's Heather Layman denied it was disappointed with the meagre sum raised after a fortnight. 'Every little helps,' she said.

In the past 12 months, Americans raised some $250bn for charity, including other foreign causes such as the Asian tsunami victims. Layman said: 'There is no financial goal. People are looking for a way to help rebuild Iraq and this is a way to facilitate that.'

The fundraising comes amid concern that some US projects in Iraq will be scrapped or only partly completed because of rising costs. Some officials fear that money may run out before key projects are completed.

Last week, the number of US troops killed in Iraq rose above 1,900.