Former Labour foreign secretary David Miliband has thrown himself into efforts to tackle the humanitarian crisis in the Philippines after his aid agency sent an emergency team to the stricken country.
The International Rescue Committee (IRC), which Mr Miliband joined in September after stepping down as an MP in April, has also launched a 10 million-dollar (£6.2m) appeal to help the victims of Typhoon Haiyan.
The typhoon struck the six central Philippine islands on Friday. Officials estimate up to 10,000 people are dead in one city alone as the full scale of the disaster, the Philippines' deadliest, becomes apparent.
Hundreds of thousands of people are also displaced after their homes were left flattened by storm surges.
Typhoon Haiyan made landfall in northern Vietnam early today as a much less powerful tropical storm, and is moving towards southern China.
Rescuers and aid agencies in the Philippines are being hampered by widespread devastation, and emergency workers faced blocked roads and damaged airports as they raced to deliver desperately needed tents, food and medicines to the devastated eastern region.
Richard Gordon, head of the Philippine Red Cross, told the BBC: "There's an awful lot of casualties, a lot of people dead all over the place, a lot of destruction.
"It's absolute bedlam right now, but hopefully it will turn out better as more and more supplies get into the area."
Mr Miliband, president of the New York-based charity, said the typhoon had caused "a human catastrophe that needs a global co-ordinated response".
He suggested that 90% of buildings had been leveled in the region where the typhoon had been hit, saying: "Hundreds of thousands of homes have been lost, water systems are broken and normal sanitation systems have failed or been flooded...
"There is now a serious risk of major public health outbreaks, which means that health systems need urgent reinforcement. The number of people affected or in danger is still emerging but the Philippines government has increased its estimate from 4.3 to 9.5 million people. And we know that more than 28 million people were within the storm's path.
"The IRC's emergency unit will start work immediately, with our partners in the region, to begin a comprehensive assessment to understand the scale of the crisis and mobilise an appropriate response. "
The IRC pledge comes after Prime Minister David Cameron offered the president of the Philippines the UK's full support in dealing with the aftermath of the typhoon.
The Prime Minister telephoned Benigno Aquino to offer the country's condolences to the victims and a promise of aid.
A Downing Street spokeswoman said: "The Prime Minister said that our thoughts are with all those affected, especially those who have lost loved ones.
"This weekend we announced a package of £6 million emergency humanitarian support to help more than 500,000 people affected by the storm.
"We have also sent four humanitarian experts to the Philippines to assist three advisers already in the country helping to co-ordinate the international response."
On Saturday International Development Secretary Justine Greening activated the UK's Rapid Response Facility (RRF) which will provide £5 million to organisations to help up to half a million victims.
Plastic sheeting to build shelters is among a £600,000 British shipment of emergency equipment.
Japan said today it would send a 25-member relief team of mostly medical staff to the Philippines to provide aid.
President Aquino visited Tacloban yesterday to see the scale of the destruction.
The typhoon struck on Friday with wind speeds of up to 170mph, triggering major landslides and knocking out power and communications.
Officials said that the death toll in Tacloban, provincial capital of the hardest hit island Leyte, could be in five figures - with hundreds or even thousands more feared killed elsewhere.