The FAO says Somalia has been worst hit by a drought in the region, where 2m need urgent food aid. The harvest there could be the lowest in a decade.

There are also food shortages in parts of Ethiopia, Kenya and Djibouti. Some 11 million need food aid, the FAO says.

A BBC correspondent in northern Kenya says corpses of cattle and donkeys are lying everywhere.

The BBC's Adam Mynott says six children have died in the past three weeks in Wajir hospital from hunger-related diseases and 15 of the 20 beds are occupied by malnourished children in varying states of health.

While trees with deep roots are still managing to push up a few scant leaves, everything else is brittle, brown and dry as tinder, he says.

BBC Africa analyst Martin Plaut says the UN agencies do not use words like "starvation" and "drought" lightly.

The FAO's Shukri Ahmed told the BBC News website that he was particularly worried because people are harvesting their crops at the moment and yet there is still not enough food.

"There should be a lull in the period of hunger," he said.

But food prices are still rising in both Somalia and Kenya, he said.

He also warned that long-term weather forecasts predicted that the next rains in April and March could be lower than normal.

'Wiped out'

In Ethiopia, some one million people in the south-eastern Somali region could face severe food shortages, while another seven million need food aid, the FAO says.

On Thursday, international aid agencies stepped up their appeal for the estimated 2.5m people needing food aid in northern Kenya.

Nearly 150,000 people - 20% of the population - face food shortages in Djibouti.

The FAO says it is conducting an urgent assessment to find out what is required to meet these people's needs.

"Communities may soon be wiped out since they depend entirely on livestock," said the Red Cross on Thursday.

Children, weakened by months of hunger, are starting to die of diarrhoea, malaria and other diseases, and the existing centres for feeding malnourished children are overflowing, aid workers say.