The Horn of Africa nation is among the most vulnerable to climate change, according to the United Nations, and in the last five years has experienced both the worst drought in four decades and once-in-a-century flooding.

In November, 750,000 people -- more than two thirds of the current number -- will be cut off from the WFP emergency food programme.

That could "tip those worst affected into catastrophic conditions," the agency said.

"We are seeing a dangerous rise in emergency levels of hunger, and our ability to respond is shrinking by the day," said Ross Smith, WFP's director of emergency preparedness and response, in a statement.

WFP leads the largest humanitarian operation in Somalia and supports more than 90 percent of the country's food security response.

"The current level of response is far below what is required to meet the growing needs," Smith said.

Government data released in August shows that 4.4 million people are facing acute food insecurity in the conflict-ravaged nation.

With about 1.7 million children under five already acutely malnourished -- including 466,000 in critical condition -- WFP said only 180,000 are currently receiving its nutritional treatment, a number that could fall even further.

Cuts to foreign aid by the United States and other Western countries this year have worsened funding problems in many developing nations.

British charity Save the Children warned in May that funding shortfalls would force it to shut more than a quarter of its health and nutrition facilities in Somalia.