Gordon Brown urged Britons to donate to an emergency appeal for the "catastrophic" quake in Haiti today as the Government announced it was giving more than £6 million in aid.
The Prime Minister said the stricken country had suffered a "tragedy beyond imagination" and called for the whole world to respond.
"The last 24 hours have been truly horrific for the people of Haiti. It is a tragedy beyond imagination," he told a press conference in Downing Street.
"I do urge people to support where they can the Disaster Emergency Committee Haiti appeal."
Meanwhile, Barack Obama has asked former US Presidents George W. Bush and Bill Clinton to aid the relief effort and says he has told top US agency and department heads to put Haiti at the top of their agenda. The US government is making an initial $100 million relief donation.
Mr Obama said "one of the largest relief efforts in our recent history" is moving toward Haiti.
He said it will take hours "maybe days" to get the full US relief contingent on the ground, because of the damaged roads, airport, port and communications. He acknowledged that "none of this will seem quick enough" to the many suffering. To the Haitians, Obama promised: "You will not be forsaken."
In London, Mr Brown said the first British search and rescue workers have arrived in Haiti to help with the aftermath of the earthquake, which is thought to have killed tens of thousands of people and left an estimated three million in need of emergency aid.
The Department for International Development has allocated £6.15 million (10 million dollars) to help the humanitarian relief work.
Mr Brown said: "The problem at the moment is that there are still many, many people who are trapped or buried under rubble, and we do not know the full scale of that catastrophe."
He insisted that Haiti now had to become "the centre of our world's attention, the world's compassion".
"We send our message of sympathy and support to the people of Haiti at this most difficult of times," the Premier said.
The Queen today offered her "profound sympathy" to the people of Haiti.
The Monarch has made a private donation to the Disasters Emergency Committee (DEC), a Buckingham Palace spokesman said, although the sum has not been disclosed.
The Queen said in her short statement: "I'm deeply saddened to hear of the earthquake in Haiti with its huge loss of life and damage to homes and livelihoods.
"I offer my condolences and profound sympathy to all those affected."
The DEC is taking donations through a special phone line, 0370 60 60 900, and through its website www.dec.org.uk .
The UK appeal will be promoted tomorrow in radio and television broadcasts, fronted by actor John Hurt and presenter Kirsty Young.
Hurt said: "This is a huge tragedy that has affected millions of people living in one of the poorest nations in the world. Please give generously so aid agencies can bring medicine, clean water and other essentials to help get these people back on their feet."
DEC chief executive Brendan Gormley said: "This huge quake has ripped apart the lives of millions of people in one of the poorest nations of the world. It is clear after the immediate rescue attempt is completed we will be left with ongoing humanitarian challenges.
"DEC member agencies and their partners are responding but face terrible suffering. We urgently need the public's help for their work."Reuse content