A clash between Yemeni troops and southern separatists, who were demonstrating on Monday against the country's reconciliation talks, left four people wounded, witnesses and a medic said.
Hardline secessionists, who are calling for independence for the south, took to the streets of the southern city of Ataq two days after a national dialogue concluded in Sanaa.
The talks concluded with a plan to turn the republic into a federation, draft a constitution and hold elections.
"The Yemen dialogue does not concern us," chanted protesters in Ataq, according to witnesses. "We reject the outcome of the Sanaa dialogue."
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A gunfight erupted between armed protesters and troops who tried to disperse the demonstration, witnesses said, adding two protesters and two soldiers were wounded.
A medic at the Ataq public hospital confirmed the toll, and said one demonstrator is in a critical condition.
Moderate factions in the Southern Movement had joined the talks, part of a Gulf-brokered exit deal that ended a year of Arab Spring-inspired protests against former president Ali Abdullah Saleh, who stepped down after 33 years in power.
But radicals have boycotted the dialogue, insisting on demanding secession for the south, which was independent between the end of the British colonial rule in 1967 and its union with the north in 1990.
A secession attempt four years later sparked a brief civil war that ended with northern forces taking over the south.