Philippines President Benigno Aquino says the death toll from Friday’s typhoon may be lower than first thought.
In an interview with CNN, he said the number of 10,000 killed was “too high” and the figure was more likely up to 2,500.
The UN says more than 11 million people are believed to have been affected and some 673,000 displaced.
The relief operation is being stepped up, but many are still without aid.
The earlier figure of 10,000 feared killed came from a police officer and local official and may have arisen from the “emotional trauma” of being at the centre of the disaster, Mr Aquino said.
He said 29 municipalities had yet to be contacted to establish the number of victims there.
The National Disaster Risk Reduction and Management Council (NDRRMC) has put the official death toll at 1,833, as of 06:00 local time (22:00 GMT) on Wednesday. The number of injured stands at 2,623 with 84 listed as missing.
Despite the increased aid effort, many survivors still badly need food, water and shelter, aid officials say.
Several countries have deployed ships and aircraft to help, but the damage to transport links and bad weather are hindering distribution of relief supplies.
“The mobilisation of air assets, clearing away the debris, opening up the routes – this is a top priority,” John Ging, director of operations at the UN Office for the Coordination of Humanitarian Affairs told the BBC.
“It’s happening. It’s happening too slowly, but it’s happening and everybody is working flat out to make it better.”
Philippine armed forces spokesman Ramon Zagala told the BBC teams were struggling to reach isolated places.
“The area is very vast and the number of helicopters, although we have a lot of helicopters at the moment, it’s really a challenge for us to bring [aid] to all the places and [bring] the number of goods that are needed.”
Tacloban – a city of 220,000 on Leyte island – is particularly badly affected.
The BBC’s Jonathan Head says the main road from the airport to the city is clogged with refugees and debris, with residents becoming angry at the lack of progress and increasing breakdown in security.
Bodies remain uncollected, local government has been wiped out and central government, which is meant to have taken over, is almost invisible, our correspondent adds.
On Tuesday the UN launched an appeal for $301m (£190m) to help survivors. It has already released $25m to meet immediate needs.
The UN Office for the Co-ordination of Humanitarian Affairs says 11.3 million people are in need of vital goods and services, because of factors such as lack of food, healthcare and access to education and livelihoods.
“We thought it was our last day”: Survivors talk to the BBC
Aid agencies have warned that the security situation is worsening. There are reports of food warehouses and grocery shops being ransacked and people starting to fear for their safety.
“There’ve been reports of attacks on food convoys and looting of aid. I think that is deterring a lot of aid agencies from getting in there,” John Cordell, from disaster relief charity ShelterBox, told the BBC.
On Tuesday, an aid convoy travelling to Tacloban was reported to have been attacked and two of the assailants shot dead by troops.
Large crowds gathered at the airport hoping to be evacuated, leading to scuffles with the security forces.
The Philippine air force has been flying transport planes in and out of Tacloban airport, carrying relief supplies and evacuating hundreds of residents.
The US is sending its aircraft carrier USS George Washington and other navy ships to help with the relief work. The carrier is expected to arrive within the next few days. The UK’s Royal Navy destroyer HMS Daring is also making its way from Singapore.
Other countries have also pledged millions of dollars in assistance.
Planes carrying aid are stuck on the tarmac in Cebu, as the BBC’s Tim Willcox reports from the airport
‘Like 2004 tsunami’
Typhoon Haiyan – named “Yolanda” by Philippine authorities – struck the coastal provinces of Leyte and Samar on Friday. It was one of the most powerful storms on record to make landfall.
It swept through six central Philippine islands before travelling through Vietnam and southern China.
Several people in both countries were killed, according to state media reports.
In the UK, the Disaster Emergency Committee (DEC) group of 14 charities launched its own appeal to help the typhoon victims on Tuesday.
DEC chairman Salah Saeed compared the destruction in the city of Tacloban to that seen after the devastating tsunami of 2004.
“There is currently no food, water or electricity. We can only imagine how much worse the situation will be for families living in towns and remote villages,” he said.