Authorities in Yemen's southern city of Aden imposed a curfew on Monday after violence blamed on suspected jihadists killed at least 22 people, pro-government media and security sources said.
Suspected Islamic State group (IS) jihadists in the city also shot dead Sheikh Ali Othman, a Sufi imam who was considered a moderate, security officials said.
The curfew will come into force at 8:00 pm (1700 GMT) and last until 5:00 am (0200 GMT), the sabanews.net website said, citing a decision by the Aden Security Commission.
The decision comes after fierce battles on Sunday in the port of Aden killed 22 people, among them 10 members of the security forces including a colonel, the security sources said.
Security sources said the clashes erupted when forces loyal to President Abedrabbo Mansour Hadi came up against resistance when they tried to deploy in the port to secure it completely.
They said the fighting lasted for several hours and that pro-Hadi forces eventually managed to take control of the facility.
Witnesses said they saw an unprecedented number of armed men in Aden on Sunday, without being able to identify them.
Hadi toured parts of the city, including the port, on Monday, according to the government news agency.
Aden, declared by the government to be the temporary capital, has seen growing unrest between Al-Qaeda in the Arabian Peninsula, long active in Yemen, and IS as both groups appear to be vying for influence.
The city was rocked by months of fighting last year between pro-government forces and Iran-backed Shia Houthi rebels who seized the capital Sanaa in September 2014 before expanding south.
Backed by a Saudi-led coalition, loyalists have regained control of Aden and four nearby provinces in the south since July as fierce fighting persists across the country.