The United Nations World Food Programme (WFP) has spoken out against the murder of the head of its office in north-western Kenya who was shot dead by unidentified gunmen, the second such killing of the agency's staff this week.

Silence Chirara, a 37-year-old father of two who was coordinator of WFP's logistics operation for southern Sudan, was ambushed on Wednesday while driving a clearly marked UN vehicle in the town of Lokichoggio. The gunmen escaped.

"We are all shocked at this savage killing of Silence Chirara and condemn it in the strongest terms," said Kenro Oshidari, WFP Representative in Sudan, who flew to Lokichoggio on Thursday.

Mr. Chirara, a Zimbabwean national who joined WFP in 1996, had worked in Iraq, Guinea-Bissau, Zimbabwe and Indonesia. He started working in Lokichoggio, a major relief hub and access route for aid delivery to southern Sudan, in March 2006.

"In all the places that Silence served, he was an incredible source of comfort and help to his colleagues. He was a valued Logistics Officer known to never step away from a challenge. This is a moment of great sorrow, for Silence's family, especially his wife and two children, friends and those at WFP who worked side-by-side with him over the years," said WFP Executive Director Josette Sheeran.

UN Security and the Kenyan police are investigating the crime.

Earlier this week, one of WFP's truck drivers in Somalia was shot dead by militiamen who stopped the agency's food convoy at an illegal checkpoint.

UN Security and the Kenyan police are investigating the crime.

Earlier this week, one of WFP's truck drivers in Somalia was shot dead by militiamen who stopped the agency's food convoy at an illegal checkpoint.