Seven people have been killed and eleven wounded after a gunman opened fire on a mosque during Eid prayers in southern Yemen, a defence ministry official has said.
The shooting in the province of Dalea came during prayers on Sunday to mark the end of the Islamic holy month of Ramadan.
Security forces said the man did not appear to be related to fighters who have been staging attacks for the past months, but no further details were immediately available.
In a separate attack on Sunday, a suicide bomber with suspected links to al-Qaeda blew himself up in the southern Abyan province, killing at least one and wounding two, an official from the province told the Reuters news agency.
The suicide bombing took place in the town of Mudiya in Abyan, the provincial official said.
"One of the dead was a local pro-army militia commander, Nasser Ali Mansur," he said.
The US has been pouring aid into Yemen to stem the threat of attacks from al-Qaeda in the Arabian Peninsula (AQAP) and to try to prevent any spillover of violence into neighbouring Saudi Arabia, the world's top oil exporter.
Last year, a US-backed offensive drove al-Qaeda offshoot Ansar al-Sharia (Partisans of Islamic Law) from cities it had seized in an uprising against former president Ali Abdullah Saleh.
Months of violent protests finally toppled Saleh, after he agreed to step down in February as part of a Gulf Co-operation Council-brokered deal, in return for immunity from prosecution.
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On Sunday, thousands of protesters returned to the streets to use the occasion of Eid to press their demands for reforms of the military and the unification of the country's army.
"This gathering here in Al-Siteen Square is in solidarity with the revolution in order to continue to push for achieving all the demands of the revolution," one of the protesters, Mohamed Al Sabri told Reuters.
"Today is a joyous Eid without deposed Ali Abdullah Saleh and some of his relatives.
"We hope we can have our next Eid without any of Saleh's relatives or sons."
The demonstrators vowed to hold the same protest twice a week until their demands are met.
"We assure the martyrs of the revolution that we are indebted to them and that as a society and people, our duty is to achieve the demands of the revolution and punish their killers as well as take care of their relatives," said another protester Abdul Naser al-Saqaf.
Abdrabu Mansur Hadi, Saleh's successor, is tasked with carrying out the country's democratisation process across all levels of the government and military.
Last week, fighters loyal to the former president took the interior ministry by force and held troops hostage.
Thirteen of the interior minister's security personnel were killed in the attack.
Southern separatist freed
Meanwhile, Yemen authorities freed a leading southern separatist overnight on Saturday, just days after he was arrested on his arrival in Aden.
Former ambassador Ahmed al-Hassani, who was arrested at dawn on Wednesday at the airport after arriving onboard a flight from Beirut, had been living in Britain since 2006 as a political refugee.
An official said that Hassani, who is the secretary general of the Southern Democratic Assembly, was freed four days later on the express orders of Hadi.
Yemen's southern separatists, although a fractured movement, have for decades complained of marginalisation by Sanaa and demand autonomy, and in some cases a return to independence, as South Yemen was before unification with the north in 1990.