UN Secretary General Kofi Annan has said that the devastation in the Indonesian province of Aceh is the worst he has ever seen.
Mr Annan witnessed the destruction of Aceh's west coast from the air
He toured Aceh on Friday with the head of the World Bank, James Wolfensohn.
Indonesia now says more than 100,000 of its citizens were killed as a result of the 26 December earthquake and tsunami.
There are fears that some aid is being hampered by the long-running conflict in Aceh between separatist rebels and the Indonesian military.
There have been reports of sporadic violence between the two sides over the last week.
Soldiers told one BBC correspondent in Banda Aceh that their relief work was being affected by attacks from separatist fighters.
The rebels in turn have accused the Indonesian military of taking advantage of the crisis to launch offensives.
ACEH: KEY FACTS
Province on the north-western tip of Sumatra
Higher percentage of Muslims than other parts of Indonesia
Gam rebels have fought decades-long separatist campaign
Year-long military crackdown beginning in May 2003 weakened Gam, but failed to capture senior members
Mr Annan said he was "shocked" by the devastation, having toured the west coast of Aceh by helicopter.
"It's a tragic event. We've seen miles and miles of destroyed shoreline," he told reporters in the western town of Meulaboh.
He said Meulaboh, which was particularly badly hit by the earthquake and tsunami, was beginning to get back on its feet but that it was still in dire need of support.
"There we saw people begin to pick up the pieces and get on with their lives and of course it shows about the resilience of the human spirit. And I believe that in time, given the support and efforts by the government and the international community, the people will be able to pick up and carry on.
For the moment, much of the survivors' rehabilitation is taking place in informal refugee camps as aid workers have only managed to so far bring a limited amount to Meubaloh, and have not yet reached other communities on the west coast.
UN emergency relief co-ordinator Jan Egeland said that there may be some 200 improvised camps in Aceh, with hundreds of thousands of people in them.
Aid agencies have called on Jakarta to set up official camps which meet international standards of hygiene, and the government said on Friday that dozens of such camps would be operational within a week.
Jakarta has pledged to set up official refugee camps within a week
A military commander in Meulaboh, Colonel Geerhan Lantara, said that Meubaloh had only 50 tents and needed at least 1,000.
The question of who provides the aid may bring its own tensions. At least two radical Islamic groups - the Indonesian Mujahideen Council, founded by jailed cleric Abu Bakar Ba'asyir, and Laskar Mujahideen - have sent relief teams to Aceh.
Relief may also be being disrupted by the ongoing rebel insurgency in Aceh. In the immediate aftermath of the tsunami both sides declared a ceasefire but there have been reports of low-level skirmishes in recent days.
Our correspondent says that the rebels do not have a strong presence in the areas that have been badly affected.
But he says that they are likely to try and raise their profile at a time when many international agencies are operating in the province.
Meanwhile, Mr Egeland said he believed the official Indonesian death toll of around 100,000 was conservative.
"I do not think we are even close to having figures as to how many people have died, how many are missing, how many have been severely affected," he said in New York.
Helicopter pilot Scott Cohick, who is helping the US military aid operation in Aceh said: "The only way to describe some of the villages is extinct."
The poor conditions in which the injured survived is also boosting the death toll.
Doctors in Banda Aceh said wounds were becoming infected, resulting in amputations, and that these operations carried their own risks.