A suicide attack at a town in south Yemen recently recaptured by the army from Al Qaida forces killed 20 people Saturday and wounded another 20, the governor of the province said.
In a separate incident in the east of the country meanwhile, a suspected US drone strike killed five Al Qaida members late Saturday, a local official said.
"Twenty people have been killed and 20 others wounded," governor Jamal Al Aqal said in a statement on the suicide attack posted on the defence ministry's website.
Officials have opened an investigation to establish a final death toll and to identify who was behind this "criminal and cowardly" attack, the governor's statement added.
Earlier, witnesses told AFP that the attack in Jaar, Abyan province, had killed eight people.
One witness said the attacker blew himself up during a mourning ceremony organised in honour of a relative of an army auxiliary leader.
"The suicide bomber belonged to the Al Qaida network," said another witness, adding that the attack was in retaliation for the local fighters' role helping Yemeni troops recapture the town.
"The victims' bodies were flying in all directions because the explosion was so powerful," said a witness who took part in the rescue operations.
The army announced in mid-June that it had recaptured Jaar and Zinjibar, Abyan's provincial capital, from Al Qaida fighters who had held it since May.
But on Wednesday, an attack by Al Qaida militants on a police station in Jaar killed two soldiers and a civilian. Locals have expressed fears that the extremists could retake the town.
In the east of the country meanwhile, an official who requested anonymity, gave AFP details of the drone attack, which he said had happened near the village of Al Qotn, in the province of Hadramut.
"A drone fired two missiles at an all-terrain vehicle... killing its five occupants, all members of Al Qaida," said the official.
Security forces deployed around the site of the strike and sealed it off, said witnesses.
The United States is the only country that has drones in the region and in recent months has been carrying out strikes on Al Qaida targets in the south and east of the country and in the Arabian peninsula.
Al Qaida militants have carried out several deadly attacks against Yemeni security services since President Abdrabuh Mansur Hadi, who has repeatedly vowed to battle extremists, came to power this year.
In July, Yemen announced it had placed its security services on high alert to prevent "terrorist" attacks after it uncovered a plot to launch assaults against security and military checkpoints.
The Yemen-based Al Qaida in the Arabian Peninsula is believed to be the most effective and lethal branch of the global network.