Yemeni security forces killed three militant leaders on Tuesday when they stormed a house used by al-Qaeda for making bombs, the interior and defence ministries said.
Yemen, a U.S. ally, has been in turmoil since a popular uprising ousted veteran ruler Ali Abdullah Saleh in February and is struggling to suppress a lethal insurgency, with the backing of Washington.
Army and security forces raided a house in the southern province of Aden at dawn, killing three militants in clashes that went on for almost two hours, the Interior Ministry said. Four soldiers were wounded.
"A large amount of various explosives was found in most of the rooms in addition to booby-trapped gas cylinders and cars ready to be used in suicide attacks and weapons including a rocket and explosive belts," the Defence Ministry website quoted a security source as saying.
The house, in Mansoura city, was used as a headquarters for al-Qaeda leaders in Aden to plan for attacks and as a bomb factory, the source said.
Security forces seized documents and computers which contained plans to attack vital establishments in the province including military, security and civil buildings, the source said.
A local security source told Reuters among those killed was a Somali fighter, adding that the cell was behind several suicide attacks and assassination attempts in Aden over the past few months.
Yemen, which borders top oil exporter Saudi Arabia and lies on major world shipping lanes, is home to al-Qaeda in the Arabian Peninsula, a group viewed by Washington as the most dangerous branch of the militant network established by Osama bin Laden.
Washington, which has pursued a campaign of assassination by drone and missile against suspected al-Qaeda members, backed a military offensive in May to recapture areas of Abyan province controlled by al-Qaeda offshoot Ansar al-Sharia (Partisans of Islamic Law).
But militants have struck back with a series of bombings and killings.
On Saturday, a suicide bomber killed himself and a bystander in south Yemen in an attempt to assassinate a government official who had targeted al-Qaeda militants.