A £52.25 million emergency aid package has been put together to help millions of drought victims in the Horn of Africa, the Government announced.
International Development Secretary Andrew Mitchell said the cash would be used to support starving people across Somalia, Ethiopia and Kenya hit by the worst drought in over half a century.
Speaking before a visit to Kenya, where he will meet Prime Minister Raila Odinga and Internal Security Minister George Saitoti, Mr Mitchell admitted the situation was "getting worse" and urged the international community to do more to tackle the crisis.
He said: "People across Britain have responded with great generosity to appeals by British NGOs (non-governmental organisations) working in the Horn of Africa.
"But the situation is getting worse - and is particularly devastating in Somalia, where families already have to cope with living in one of the most insecure countries in the world.
"More than 3,000 people every day are fleeing over the borders to Ethiopia and Kenya, many of them arriving with starving children.
"The international community must do more to help not only refugees but also those victims of the drought who remain in Somalia."
The Dadaab camps in Kenya are overflowing with tens of thousands of refugees fleeing the parched landscape in the region where Somalia, Ethiopia and Kenya meet.
The World Food Programme estimates that 10 million people already need humanitarian aid and the UN Children's Fund believes more than two million youngsters are malnourished and in need of life-saving action.
The Department for International Development (Dfid) said the cash would go towards helping 500,000 people in Somalia, including treatment for nearly 70,000 acutely malnourished children.
It will also be used to provide clean drinking water and health care for more than 130,000 people in the Dadaab camps.
In Ethiopia, around 100,000 people in Dolo Ado refugee camps will be helped with access to shelter and clean drinking water as well as targeted treatment of starving children.
The package will also be used to support around 300,000 Kenyans, including special rations to prevent malnutrition in children under the age of five and breastfeeding mothers.
The Secretary of State is visiting Kenya with Brendan Gormley, head of the Disasters Emergency Committee (DEC), and Justin Forsyth, chief executive of Save the Children and will meet Somalian refugees.
Mr Gormley said: "The need to scale up the response to this disaster is urgent so I am extremely pleased that the Secretary of State has announced this further UK Government funding today.
"Combined with the extraordinary generosity of the UK public to the DEC East Africa Crisis Appeal, we can truly say that the UK is playing a leading role in responding to this disaster.
"There is still, however, a great deal more to be done before we can say we have safeguarded the lives of the 10 million people at risk."
Mr Forsyth said: "Over the past few days, I've seen first hand the enormous suffering the drought is causing in the Dadaab refugee camp and across northern Kenya.
"Families I've met are absolutely desperate for food and water, and we know that the situation in Somalia is even worse.
"The UK Government's extremely welcome announcement, combined with the overwhelming response of the British people, will help save hundreds of thousands of lives threatened by the worst drought in living memory."
Mr Forsyth said: "There are 400,000 people here in the Dadaab camp.
"It is the size of Bristol and this is just the tip of the iceberg, the levels of severe malnutrition in the region are increasing."
He also praised the "unbelievable generosity" of the British public, who have donated £13 million to the DEC East Africa Crisis Appeal launched a week ago.
"This money saves lives but I think we can still do more to help people in East Africa," he added.