By Heather Sharp
BBC News, Jerusalem
Even as aid agencies struggle to meet the immediate needs of those left injured, homeless and traumatised by the Israeli operation in Gaza, concerns are growing that reconstruction efforts could become bogged down in a complex political tangle.
Initial Palestinian estimates said rebuilding would cost $2bn (£1.4bn) and take three to five years, even without the host of obstacles Gaza faces.
International agencies are still assessing the scale of the destruction in preparation for a drive for reconstruction pledges.
But with the international community refusing to deal directly with Hamas, the militant group which controls Gaza, it remains unclear how the money could be spent.
Israel is determined that Hamas should in no way benefit from international aid funds. It also controls everything entering the Gaza Strip.
It is demanding strict controls on building materials - urgently needed before the fighting and now required in vast quantities - which it says could be used to build rockets and launching sites.
Waiting to see
Then there is the long-standing feud between Hamas and the West Bank-based Palestinian Authority (PA) - both battling for popularity among Palestinians and vying for international recognition.
Hamas spokesmen say they are the legitimate authority in Gaza and the PA is corrupt and cannot be trusted with reconstruction money.
US President Barack Obama and the European Union favour channelling aid through the PA - although the European Commission Representative in Jerusalem, Christian Berger, said the EU was waiting to see the outcome of Egyptian-brokered reconciliation talks between the Palestinian factions.
But as Hamas has purged PA figures from many of Gaza's institutions, it remains unclear what the PA could achieve on the ground.
Along with Israel, the US and EU regard Hamas as a terrorist organisation.
The Middle East Quartet, which brings the US and EU together with the UN and Russia, refuses to talk to Hamas unless it renounces violence and recognises Israel's right to exist.
But UN agencies do co-ordinate with Hamas, which won elections in 2006 and consolidated its control in Gaza by force a year later.
'Dealing with the authorities'
UN relief agency Unrwa says it has contacts with Hamas "even at ministerial level", but strictly on technical issues related to the delivery of its humanitarian services in line with wider UN policy.
Some of the World Food Programme's food aid distributions in Gaza are carried out by civil servants at the Ministry of Social Affairs, which, in Gaza, is controlled by Hamas.
All goods have to pass through Israel's fortified cordon around the Gaza Strip
The WFP says strict monitoring procedures ensure its aid reaches the people it is intended for. The agency emphasises that there were no direct contacts with Hamas, and its activities in Gaza were agreed with the PA before Hamas took over in Gaza.
"In every country that we work in, we deal with the authorities - so in Gaza we deal with the Ministry of Social Affairs," said WFP spokesman Robin Lodge.
"If the next question is 'Are they Hamas?', then the answer is 'Yes they are'," he adds.
The EU, a major donor which has spent 3bn euros ($3.9bn, £2.8bn) in the Palestinian territories since 2000, channels much of its funding through such UN agencies.
It is widely expected that the UN's agencies - including the UN Office for the Co-ordination of Humanitarian Affairs, UN Development Programme, and the World Health Organization - will end up playing a major role in Gaza's reconstruction.
But even Unrwa, which has the largest UN presence in Gaza, is primarily focused on - and experienced in - food aid, schools and primary health clinics, not major construction projects.
"I don't think they have the capacity by themselves," says political analyst George Giacaman of Birzeit University.
A further question is whether the rebuilding of the roads, health, education, water, power and sanitation infrastructure can be carried out by UN agencies if their contacts with Hamas are limited only to essential, technical co-ordination for the delivery of humanitarian services.
"Some projects may well be feasible, others will be very difficult," says the WHO's acting head of mission, Tony Laurance.
He gives the example of training programmes for medical staff: "It looks like a fairly straightforward activity - but still requires the assent of the relevant authorities."
And if past experiences are anything to go by, the power struggle between Hamas and the PA is likely to further complicate matters.
Last year strikes by teachers and doctors in protest at the replacement of key staff with Hamas loyalists disrupted health and education services.
And the UN had to step in to supply fuel for water pumps because a row over control of the Palestinian Water Authority paralysed some of the body's operations.
The PA and Hamas have both accused each other of diverting aid for their own benefit, according to Israeli press reports.
Egypt is pushing to broker some form of unity government, but the sides remain far apart.
Massive problems with Gaza's sewage system prompts serious health worries
Hamas has, however, indicated it may support the formation of a Palestinian body, including the Arab League, to manage funding.
A further problem is bringing in the necessary construction materials and spare parts for things like generators, sewage plants, power infrastructure and medical equipment.
A solution to the question of the crossings into Gaza is a key issue in ceasefire talks.
Hamas wants the total lifting of Israel's 18-month blockade, which permits little more than food, grain and medicines to enter Gaza. Israel wants to ensure Hamas cannot re-arm if borders are re-opened.
Israeli Defence Ministry spokesman Peter Lerner stressed that Israel wanted "each and every pipe accounted for", along the lines of a project-by-project approvals process used for a small number of projects in the past.
But international aid officials say the approach was inadequate before the war, and fear it will spell disaster for reconstruction attempts on the necessary scale.
For Gaza's health system as a whole - much of which is run by the Hamas-controlled Ministry of Health - it would be "a nightmare," says Mr Laurance.
"The health sector has not been able to get essential medical equipment into Gaza¿ it can be incredibly convoluted going through these approval procedures," he said.
The prospects for reconstruction hang on the outcome of the political process, but it remains unclear when - and what - it will eventually deliver.
"What may happen is that ordinary people will suffer - we're witnessing the political interests of the parties taking precedence over the actual work that is needed," says Prof Giacaman.