Gunmen fired at southern separatists in Aden and accidentally killed a civilian on Tuesday, as Yemen's army and police patrolled the city's main streets, witnesses and activists said.
President Abdrabuh Mansur Hadi, meanwhile, met with Southern Movement representatives on the fourth day of an unannounced visit to the restive region, according to a member of the secessionist group.
Activists from the Southern Movement blamed plainclothes police for shooting dead the civilian who they said had worked as a guard at a building in Aden's Mansura district.
The shooting came as dozens of southern protesters blocked roads with stones and burnt tyres in Mansura, as well as the neighbourhoods of Sheikh Osman and Dar Saad, an AFP correspondent reported.
Police and troops were heavily deployed across the city's main roads, but there no reports of any violence, witnesses said.
Unrest intensified across the south from Thursday when protesters marking the first anniversary of the ouster of former strongman Ali Abdullah Saleh clashed with police in Aden.
Nine people have been killed in the clashes so far.
Residents of Aden said some roads were reopened later on Tuesday and that life was returning to normal.
Hours after Tuesday's incident, southern separatists said they would suspend their campaign of "civil disobedience" but threatened to escalate it if the authorities failed to meet their demands by March 1.
"We have suspended our civil disobedience across southern cities until March 1 to demand the implementation of our demands," Southern Movement activist Nizar Haitham told AFP.
"If our demands are not met, there will be an overall escalation starting on Saturday across all southern provinces," he said.
Hadi, who replaced Saleh, is on an "inspection visit" to the region -- his first since becoming president -- in an attempt to contain the violence which threatens to disrupt a national dialogue set to take place on March 18.
"We met Hadi during the weekend and demanded sacking Aden governor and its central security services chief," said Lutfi Shatara, a representative of the Southern Movement at the dialogue.
The southerners also demanded "government compensation to families of the victims" of the latest violence and "the release of all political prisoners," he said.
Shatara said Hadi had promised to take "measures to calm the south ahead of the dialogue. But nothing has been done so far, which is not encouraging."
The national dialogue is stipulated in the UN-backed Gulf initiative that eased Saleh out of office after more than three decades in power.
The dialogue aims at drafting a new constitution and electoral law for parliamentary and presidential polls in 2014.
But hardliners in the south have refused to take part in the dialogue and have called for civil disobedience, insisting on a secession of the regions of the formerly independent south.
South Yemen broke away in 1994, sparking a civil war, before it was overrun by northern troops.