Four UN aid workers, including two westerners, were kidnapped by unknown gunmen in the southern Somali town of Wajid as they were preparing to leave Somalia for neighboring Kenya, local UN officials said Monday.

The four, also including a Somali and a Kenyan citizen, work for World Food Programe (WFP) and UN Development Programe (UNDP) and were at a local airstrip when they were seized by the gunmen, a local UN official who refuse to be named told Xinhua.

The official refused to disclose the nationality of the two westerners, saying he was afraid that may endanger them.

The area is under the control of the Somali insurgent group of Al-Shabaab who has not yet commented on the abduction of the aid workers in territory under their rule.

A number of aid workers and journalists have previously been abducted in the volatile south Somalia where some of them are being held for ransom.

Foreigners are abducted in Somalia mainly for ransom and are treated well in expectation of the hefty ransom money often demanded by their captors.

(Xinhua News Agency March 16, 2009)