The UN's World Food Programme (WFP) has suspended its work in much of southern Somalia due to threats against its staff and unacceptable demands by al Shabaab rebels controlling the area, a WFP spokesman said on Tuesday.
The WFP has been central to international efforts to address an acute humanitarian crisis in the drought- and conflict-torn Horn of Africa nation. Experts say half the population need aid.
"Unacceptable conditions and demands from armed groups have disrupted WFP's ability to reach many of the most vulnerable people in southern Somalia," Peter Smerdon said.
"Despite this suspension, WFP remains active in much of central and northern Somalia, including the capital, Mogadishu."
But he said it was now virtually impossible to reach up to 1 million highly vulnerable women and children. About three-quarters of the 3.76-million Somalis who need aid are concentrated in central and southern regions.
Most of those areas are controlled by the al Shabaab rebel group, which Washington says is al Qaeda's proxy in Somalia.
Fighting in the country has killed 19,000 civilians since the start of 2007, and driven another 1.5 million from their homes. Amid the chaos, Western security agencies say it has become a safe haven for Islamist militants, including foreign jihadis.
Smerdon, the WFP spokesman, said al Shabaab controlled 95% of the territory, where its work had been disrupted. In November, the rebels issued a string of conditions for aid agencies operating in the south.
"These included removing women from their jobs and a demand for a payment of $20,000 every six months for security," Smerdon said, adding that Shabaab elders later demanded that WFP and its contractors cease all their activities on January 1, 2010.
He said WFP took that deadline seriously.
"The food stocks are out... Most equipment has been brought out and vehicles have been brought, as well as obviously all our staff," he said. "Staff safety is a key concern for WFP."
The turmoil in Somalia has spilled into the waters of the strategic Gulf of Aden and Indian Ocean, where Somali pirates have driven up insurance costs and made tens of millions of dollars in ransoms by hijacking ships and their crews.
A former Islamist rebel, Sheikh Sharif Ahmed, was elected president in January. While there were hopes he would be able to reconcile with the insurgents, he has made little headway, and his government controls only a few blocks of Mogadishu.
