MOGADISHU - Up to 60 Somali intelligence officers stormed a U.N. compound in Mogadishu on Wednesday and seized the World Food Programme's local chief of operations at gunpoint.

Riding in two technicals -- Somalia's version of tanks -- armed security officers forced their way into U.N. offices before taking the Somali head of WFP operations in Mogadishu to intelligence headquarters where he was being held in a cell.

WFP said it was unclear why Idris Osman had been taken away, and called for his immediate release.

"WFP has not received any explanation for this action, which violates international law," the agency said in a statement.

WFP said it was forced to suspend food distribution, which started on Monday, to more than 75,000 people in the capital -- WFP's first distribution of food since late June.

"In the light of Mr. Osman's detention and in view of WFP's duty to safeguard its staff, WFP is forced immediately to suspend these distributions and the loading of WFP food from our warehouses in the Somali capital," it said.

A police spokesman confirmed Osman's detention. He declined to say why he had been seized.

Violence has forced many aid agencies to quit the Horn of Africa country, leaving U.N. agencies and a few others to run limited operations staffed by locals.

Rampant piracy, closed borders and the authorities' previous failure to clear food shipments for distribution have hobbled efforts to provide aid to thousands of Somalis who have fled an Islamist-led insurgency in the capital.

In April, the interim government promised it would clear obstacles to delivering aid after the U.N.'s humanitarian chief complained about red tape and restrictions.

Those include numerous checkpoints where aid workers complained of theft or obstruction, a longstanding practice of Somali gunmen in the 15 years of anarchy since dictator Mohamed Siad Barre was deposed.

The humanitarian situation has worsened since joint Ethiopian-Somali forces routed rival Islamist leaders from their southern strongholds in January and spawned an insurgency by remnants of the sharia courts movement.

Many Somalis condemn the government -- the nation's 14th attempt at central rule since 1991 -- for failing to end insecurity, improve health and education, and bring peace.