Yemeni troops shot dead a southern separatist in clashes that erupted in Aden on Saturday when activists blocked roads in a campaign of "civil disobedience" to protest the killing of five people.
"One man was killed and two others were wounded by gunfire," a medic at Aden's Al-Naqib hospital told AFP on condition of anonymity.
Activists from the separatist Southern Movement confirmed the casualties belonged to their group which calls for autonomy or the complete independence of the south.
Aden residents said dozens of separatists took to the streets in the districts of Khor Maksar, Mualla, Sheikh Osman and Dar Saad early on Saturday, blocking roads and burning tyres, prompting clashes with the army.
Residents in Mansura district spoke of "very fierce clashes" ongoing in their area between the army and separatists.
A security official told AFP that "supporters of the Southern Movement blocked roads and, when the army tried to intervene, gunmen among them deployed in buildings in these areas opened fire on troops, prompting clashes."
The official, who asked not to be named, said the protesters were supporters of the hardline separatist faction led by exiled Ali Salem al-Baid, which has so far been refusing to take part in a national dialogue set to take place on March 18.
The activists are protesting "under the banner of civil disobedience," the official said.
Lutfi Shatara of the Southern Movement told AFP that "there is civil disobedience in Aden in protest against the February 21 massacre," referring to the killing by police of five people -- including four activists -- during pro-independence protests.
"People are angry at local authorities," he said.
Thursday's protests were to mark the first anniversary of the ouster of autocratic president Ali Abdullah Saleh.
South Yemen broke away in 1994, sparking a civil war, before it was overrun by northern troops.
Similar clashes were also taking place in Mukala, capital of the southeastern Hadramawt province, witnesses there said, adding separatists had burnt down two offices belonging to the Islamist Al-Islah (Reform) Party, which backs President Abdrabuh Mansur Hadi.
There were no reported casualties in Hadramawt, however.
The Southern Movement has been divided over participating in the national dialogue.
All its factions had finally agreed to join the UN-backed talks except for Baid's faction which insists on the complete independence for the south where residents complain of discrimination by the Sanaa government.
The conference, originally set for mid-November, has been repeatedly delayed, mainly due to differences with the southerners.
Saleh was formally replaced by Hadi, himself a southerner, on February 21, 2012 after a year-long deadly uprising to oust him, under a UN-backed power transition agreement brokered by the Gulf Cooperation Council that called for a two-year transition.
During a speech in Aden to mark one year in power, Hadi on Thursday denounced "calls for armed conflict, which will lead to the loss of the southern cause," in an apparent reference to Baid's faction.