By Paul Reynolds
World Affairs correspondent, BBC News website
There is often a difference between aid promised to victims of disasters and aid actually delivered - but the reasons for this are more complex than broken promises.
The problem is not so much evident in the early aftermath when the task is to get the resources and get them to the right places and quickly.
Governments often struggle to deliver useful long-term aid
It mainly concerns long-term reconstruction aid.
Oxfam's policy director James Ensor, who is in Jakarta for the tsunami donors' conference, said that governments must be held accountable if they do not spend the money they promise.
"Ordinary people around the world have donated hundreds of millions of dollars to assist the tsunami survivors. They have every right to be outraged if their government's promises made today in Jakarta do not materialise," he said.
However, according to experts, it is not only the pledging governments that have a role.
Malcolm Rodgers, a senior officer for emergencies at Christian Aid in London, says there are three main reasons for the discrepancy between money pledged and money received.
"The first is the lack of absorptive capacity in the receiving countries. The ability of local administrations to function in some places might have been wiped out. Work sometimes just cannot be undertaken or completed.
"The second is that donor countries can set conditions. For example, they say that a project has to be carried out by their own consultants or companies and within a set time.
"Or they might decide that a project is not actually doing much good and abandon it. One could call this donor fatigue. If the conditions are not met, the aid is not given.
"The third is that the attention of the governments is distracted by other disasters and events and money gets shuffled around to meet those needs."
The discrepancy is evident in many major disasters. After Hurricane Mitch in Central America in 1998, a donor's conference in Stockholm the following year promised $9bn in aid.
According to Malcolm Rodgers, who wrote a report on the aftermath of Mitch, only about 30 to 50% of that money has been spent.
MAIN AID PLEDGES
EU: $30m already being spent on the ground, $132m in short-term aid, $455m for long-term reconstruction
Australia: $764m, distributed over five years, half the sum in loans
Germany: $674m in aid over the next three to five years
Japan: $500m - half in bilateral aid, half through multilateral institutions
US: $350m in debt relief, no time scale given
UK: $96m in aid of which $13m spent so far, hundreds of millions more promised
A year ago, the ancient Iranian city of Bam was hit by an earthquake and $1bn promised.
The estimates as to how much has reached Bam range from as low as $17m to just $115m.
However, a closer look at what happened in these two events shows the complexities of reconstruction.
A World Bank report on Honduras, for example, blamed both conditions set by donors - time limits among them - and the over-ambitious aims of reconstruction.
"The objective was probably unrealistically ambitious for a country in crisis," it concluded.
Up to half the money pledged after Hurricane Mitch was not spent
That meant in practice that Honduras was simply not able to spend all the money on offer.
The report said: "The quality of reconstruction work has been varied, often seriously inadequate."
It speaks of rushed projects and a lack of consultation with local people, and criticises organisations for sending people who could not speak Spanish.
In the case of Bam, another factor has come into play. This is the plan drawn up by the Iranian government to rebuild this historic city.
Such a plan cannot be implemented within a year. So the level of aid actually taken up appears to be limited to temporary measures. That is why people are still living in shelters not houses.
Another factor is referred to in a World Bank report - the preference of the Iranian government to seek its own sources of finance.
That said, however, the World Bank approved a $220m reconstruction loan for Bam last September. So eventually more money should be available. But the delay will probably mean that some of the original pledges will lapse.
By general agreement it seems that the problem of failing to deliver on pledges applies much less to non-governmental organisations.
This is partly due to the smaller sums involved. But, in the case of British charities, they are bound by rules stipulating that a percentage of the aid - usually 80% - has to be spent within six months and the rest spread out.
Some argue for a more flexible system but at least the charities know what they have to do.
Governments, in the view of some charities, are too free with their promises. John Davison of Christian Aid said bluntly: "Pledges are cheap."
Hugh Goyder, an independent development consultant in Oxford, implies that it is too easy to pledge.
The Bam quake in 2003 killed 20,000 and destroyed ancient sites
"Driven by the media coverage of the tsunami and the humanitarian response this evokes, every leader offers a bigger and bigger figure.
"There has been leap-frogging, even an excess of offers. I am concerned at how all this money will be spent once the media circus has moved on.
"The problems of co-ordination are huge. There is the risk of multiple funding of the same project. In Indonesia we also have to avoid corruption for which it is well known.
"Turning money into houses and livelihoods is a long and difficult process. We need more realistic expectations."