Somalia's extremist Islamist militia on Tuesday vowed to avenge the killing in a US military operation of one of Al Qaeda's top regional leaders, Saleh Ali Saleh Nabhan.
"Muslims will retaliate against this unprovoked attack," a top leader of the Shebab, an extremist movement with suspected links to Al Qaeda, told AFP on condition of anonymity.
"The United States is Islam's known enemy and we will never expect mercy from them, nor should they expect mercy from us."
According to US officials, Saleh Ali Saleh Nabhan, a Kenyan citizen wanted by the FBI as a mastermind of the deadly 2002 anti-Israeli attacks in Mombasa, was killed in a US military operation on Monday in southern Somalia.
"We are investigating the matter and if any Somali is found to have aided the attackers, then he or she shall face Allah's verdict," he warned.
The Shebab official refused to elaborate on the circumstances of the operation, in which several other extremist militants are believed to have died.
The area about 200 kilometres (120 miles) south of the capital Mogadishu where Nabhan was killed is firmly under the control of the Shebab.
The Shebab group finds its roots in Somali Islamist movements created more than two decades ago but has existed as such for four to five years.
The Shebab -- whose commanders were trained and fought in Afghanistan -- spearheaded the bloody resistance against Ethiopia's two-year occupation of Somalia and are now involved in a deadly insurgency against the government.
Some of its leaders claim links to Al Qaeda and the movement is known to have sheltered known Al Qaeda operatives such as Fazul Abdullah, wanted over the Mombasa attacks as well as the deadly 1998 US embassy bombings in Nairobi and Dar es Salaam.