A leader of Yemen's Southern Movement said on Saturday he was withdrawing from talks to draft a new constitution in protest at a "plot against the southern cause," he said.
In a statement obtained by AFP, Ahmed bin Farid al-Suraimah said he had pulled out of the talks, which began on March 18, because they "avoid tackling the rights of southerners to self-determination."
"The current dialogue is aimed only at reproducing a system similar to the one that exists now," he said.
But Suraimah, who presided over the committee responsible for the southern question, said his withdrawal was personal and not on behalf of his group which is led by Mohammed Ali Ahmad and is still represented at the talks.
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Most southern factions finally agreed to take join the national dialogue after months of negotiations and under UN pressure.
But Southern Movement hardliners led by the former South Yemen's ex-president Ali Salem al-Baid have dug in their heels, insisting instead on negotiations between two independent states in the north and south.
Supporters of southern independence often stage demonstrations against the national dialogue, especially in Aden.
After the former North and South Yemen united in 1990, the south broke away in 1994, triggering a short-lived civil war that ended with the region being overrun by northern troops.
The dialogue, scheduled to run six months, brings together 565 representatives of Yemen's various political groups, from secessionists in the south to Zaidi Shiite rebels in the north, as well as civil society representatives.