(Adds U.S. drone strike, background)
ADEN, Aug 5 (Reuters) - A suicide bomber struck at a funeral in a village in Yemen's southern province of Abyan overnight, killing at least 18 tribal fighters, officials and residents said on Sunday.
The bomber targeted tribesmen who fought alongside the Yemeni army during an offensive against al Qaeda-linked militants in Abyan in June that the government hailed as a major victory.
To the east of Abyan, a U.S. drone fired on a vehicle carrying suspected militants in the province of Hadramout, killing its three passengers, said a local official.
"The charred bodies of three men from (the militant group) Ansar al-Sharia were found and the car they were in was destroyed," said the official.
The United States and Saudi Arabia increasingly view the impoverished country as a front line in their war on al Qaeda and its affiliates.
Ansar al-Sharia (Partisans of Islamic Law) seized several towns in Abyan last year while then-President Ali Abdullah Saleh was busy grappling with mass protests that eventually toppled him.
The United States supported the military campaign that drove the Islamist fighters from their strongholds in June, but residents and analysts say the militants are simply lying low and waiting for a chance to regroup.
(Reporting by Dhuyazen Mukhashaf; Writing by Isabel Coles; Editing by Ralph Gowling)