More than 100 people have died from hunger in the past 48 hours in a single region of Somalia, the country's prime minister said.
It is the first death toll announced in a severe drought threatening millions of people across the country.
Somalia's government declared the drought a national disaster on Tuesday. The United Nations estimates that five million people in the Horn of Africa nation need aid, amid warnings of a full-blown famine.
The United Kingdom has allocated £100 million to humanitarian funding for Somalia, which is providing emergency food to up to a million people.
The money is also giving life-saving nutritional support to more than 600,000 starving children and pregnant and breastfeeding women, safe drinking water for a million people and emergency healthcare for 1.7 million people.
The death toll of 110 announced by prime minister Hassan Ali Khaire is from the Bay region in the south west of the country.
Somalia was one of four regions singled out by the UN secretary-general last month in an aid appeal to avert catastrophic hunger and famine, along with north-east Nigeria, South Sudan and Yemen.
All are connected by a thread of violent conflict, the UN chief said.
UN humanitarian co-ordinator Stephen O'Brien is expected to visit Somalia in the next few days.
Thousands have been streaming into the capital Mogadishu in search of food aid, overwhelming local and international aid agencies.
More than 7,000 internally displaced people checked into one feeding centre recently.
The drought is the first crisis for Somalia's newly elected Somali-American leader, President Mohamed Abdullahi Mohamed.
Previous droughts and a quarter of a century of conflict, including continuing attacks by extremist group al-Shabab, have left the country fragile.
Mr Mohamed has appealed to the international community and Somalia's diaspora of two million people for help.
About 363,000 acutely malnourished children in Somalia "need urgent treatment and nutrition support, including 71,000 who are severely malnourished", the US Agency for International Development's Famine Early Warning Systems Network has warned.
Because of a lack of clean water in many areas, there is the additional threat of cholera and other diseases, UN experts say. Some deaths from cholera have already been reported.
The government has said the widespread hunger "makes people vulnerable to exploitation, human rights abuses and to criminal and terrorist networks".
The UN humanitarian appeal for 2017 for Somalia is £702 million to provide assistance to 3.9 million people, but the UN World Food Programme recently requested an additional £21 million to respond to the drought.
UK International Development Secretary Priti Patel said: "More than six million people in Somalia are living in desperate conditions, with the number of people tragically dying from hunger increasing and many more lives threatened.
"The UK is a world leader on humanitarian aid and we are leading the world by supporting the famine-stricken areas in Somalia and providing essential emergency assistance.
"Our message to the international community is clear - they need to act now and urgently, before it is too late to help stop innocent people starving to death."