Tributes were paid today to the first Briton confirmed to have died in the Haiti earthquake as the Government trebled the amount of money it is giving in aid to more than $32m (£20 million).
United Nations worker Frederick Wooldridge, 41, from Kent, was "committed" to helping the developing world, his family said.
The increase in funding from an initial $10m (£6.2 million) for the disaster-struck country will be announced at today's meeting of European Union development ministers in Brussels.
International Development Secretary Douglas Alexander said: "It is now clear that the international community is dealing with an almost unprecedented level of devastation.
"Our initial assessments show a level of humanitarian need which would severely test the international response in any circumstances. But the impact of this earthquake is magnified because it has hit a country that was already desperately poor and historically volatile.
"To address the needs of the immediate humanitarian response the UK Government will pledge a further $20m, on top of the $10m initially donated."
Mr Wooldridge worked for the UN in Geneva and Liberia before moving to Haiti in 2007.
His family said he "loved" his work as a Senior Political Affairs and Planning Officer on the island.
They said: "Frederick was committed to helping developing countries to build better futures for their peoples.
"Frederick was a much-loved member of a close family. He leaves behind his wife, his parents, brother and sister, grandmother and extended family. He had many friends in the UN and beyond, particularly Geneva where he loved skiing and mountaineering."
Mr Wooldridge's wife posted a photograph of her husband on a Facebook group for relatives of UN workers based in Haiti.
Teamar Melles wrote: "Anxiously waiting for good news about my husband Frederick Wooldridge, Political & Planning Section who was at MINUSTAH HQ at the time of the earthquake. Please please!"
After his death was announced, friends began to leave tributes on the site.
One, Alaa Nasser wrote: "RIP .. lovely memories lasts for ever .. Teamar, he will always live in your wonderful lively spirit."
Another, Eric Mouillefarine described Mr Wooldridge as an "outstanding person".
A Downing Street spokesman said the Prime Minister's thoughts were with Mr Wooldridge's family and friends.
There is still no news of another British UN worker missing in Haiti.
Relatives of Ann Barnes, 59, said they fear the worst as she has been unaccounted for since the earthquake hit Haiti on Tuesday.
A British member of one of the rescue teams scouring the shattered island for survivors said the chances of still finding people alive will "fall massively" as the days go on.
Dan Cooke, a Wiltshire firefighter working with a team from Rapid UK, said his team rescued two people on Saturday and two on Friday.
He said: "It is more than we would usually come across. The people are very tough as a nation and the weather conditions help to keep people alive but as the days go on the chances of people surviving fall massively.
"There are 1,700 rescue workers here and there is work for everyone which gives some sense of the scale of what has happened."
Mr Cooke's team used hammers and chisels to free a woman trapped beneath a collapsed concrete building in Port-au-Prince.
It took them six hours to dig the 39-year-old woman out.
He said: "It's a great lift but people think it's like scoring a point or scoring a goal and it's not.
"The moment you've done that you look around and see there is something else to do.
"It doesn't change the fact this is a catastrophe."
Mr Cooke said his team was one of 47 working across the capital in often dangerous conditions.
He said: "You hear gunfire, you see gangs of youths carrying machetes but to some extent that is part of the culture here.
"We are doing quite well. The UN security forces are attaching themselves to us and some teams have brought their own armed security.
"We have been working with other teams and local people and they have been fantastic.
"The conditions were very hot and dusty. There is always a smell of the dead and sometimes it is extremely potent.
"There are some very horrific scenes."
The chief executive of the British Red Cross said "a measure of law and order" was vital to the success of the aid effort.
Sir Nicholas Young told BBC 1's Andrew Marr Show the British people had supported the fundraising campaign "incredibly generously" but that had to be backed up by organisation on the ground.
He said: "The need is to get the aid out from the airport to the people and to get it out in an orderly way that makes sure those most in need get it.
"A measure of law and order on the streets is absolutely vital.
"These are desperate people in desperate circumstances and the sooner we get a reliable pipeline of aid out to them the better."
The Department for International Development (DfID) said £2 million in aid pledged by the UK Government would be spent on providing logistical support and communications to help speed up the distribution of supplies.
Oxfam teams gave out water to thousands of people in the capital yesterday and aid workers from Concern Worldwide distributed 2,000 jerry cans and 100,000 water purification tablets.
A cargo plane chartered by humanitarian organisation Action Against Hunger with 20 tonnes of aid aboard arrived in Port-au-Prince at noon on Saturday.
More sanitation equipment will be flown out from East Midlands Airport tomorrow.
The DEC Haiti Earthquake Appeal total now stands at £15m with £10m raised in the space of 24 hours from Friday.
DEC chief executive Brendan Gormley said: "Once again people in the UK have proven that they will not sit idly by in the face of widespread suffering. The amount raised so far is a tremendous show of generosity and that money is already beginning to be put to work. We urgently need people to keep donating to ensure that the people of Haiti get all the aid they need.
"We know that aid is beginning to get through, with more supplies arriving today. The challenges on the ground are still large, but our member agencies are well placed to respond and get life-saving material out to where it is needed most. For those who have not yet made a donation, there is still time and there is still need."
Haitian President Rene Preval implored the international community to better co-ordinate the massive aid effort for his country and not to squabble over how to provide it.
US Secretary of State Hillary Clinton said there were still no official estimates of the death toll because unofficial figures of 100,000 may turn out to be too low.Reuse content