The President of the Philippines, 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.
So where is the aid? That was the question on everyone's
lips in the district of Pawing, outside Tacloban.
Nearly every house has either been flattened or left
without roofs or windows. People are living amid the
sodden debris that was once their homes.
They are wet, hungry, and increasingly angry. I watched
them making the long trek into Tacloban in search of food,
and returning empty-handed. One long queue outside a
food warehouse quickly broke down into a free-for-all,
people grabbing whatever they could.
The local government was pretty much wiped out by the
typhoon. That's why the central government has taken
over the running of Tacloban. But it is almost invisible.
Without power or phone communications, people have
no idea whether anything is being done for them.
The airport, while badly battered, is functioning. Planes
come and go, several every hour. But they are not
bringing much in, only taking people out. The Philippine
army and police are very visible there, much less so in
the rest of the city.
By day five of a disaster like this, you would expect to
see some preparations for a scaled-up aid programme
at the airport. There are still very few signs of that here.
Instead, there are still corpses, lying uncollected, at the
end of the runway.
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 1,798, as of 22:00 local time (14:00 GMT) on Tuesday. The number of injured stands at 2,582 with 82 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."
Tacloban - a city of 220,000 on Leyte island - is particularly badly affected.
The BBC's Jonathan Head described how the main road from the airport to the city was 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 says.
Earlier, the UN launched an appeal for $301m (£190m). It has already released $25m to meet immediate needs.
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.
An aid convoy travelling to Tacloban is reported to have been attacked and two of the assailants shot dead by troops.
The damage to infrastructure is making the aid effort more difficult
Thousands of survivors desperately need food, water and shelter
Some survivors have sought shelter in a convention centre in the ruined city of Tacloban, on Leyte island
Residents of Tacloban, desperate to leave, were restrained by police at the airport
Large crowds gathered at the airport hoping to be evacuated, leading to scuffles with the security forces.
The Philippines air force has been flying C-130 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. Japan is providing $10m and Australia $9m in humanitarian aid, while New Zealand has pledged over $1m.
'Like 2004 tsunami'
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.
AUSTRALIA: $9.3m package, including medical staff,
shelter materials, water containers and hygiene kits
JAPAN: $10m, including tents and blankets. 25-person
medical team already sent
SOUTH KOREA: $5m plus a 40-strong medical team
INDONESIA: Logistical aid including aircraft, food,
generators and medicine
UAE: $10m in humanitarian aid
US: $20m in humanitarian aid, 90 marines, aircraft
carrier plus logistics support
UK: $16m (£10m) package including emergency shelter,
water and household items
Hundreds of thousands of people were evacuated before the typhoon arrived, but many evacuation centres were unable to withstand the winds and storm surges.
Haiyan brought sustained winds of 235km/h (147mph), with gusts of 275 km/h (170 mph) and waves as high as 15m (45ft).
The typhoon then headed west, sweeping through six central Philippine islands and into Vietnam, where state media said at least 13 people had died.
At least six were also reported killed in southern China, after Haiyan tore through Hainan province and the Guangxi Zhuang autonomous region over the weekend, 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.