Yemeni police shot dead six activists in Aden on Thursday during clashes with protesters calling for southern independence on the first anniversary of the ouster of autocratic leader Ali Abdullah Saleh, their movement said.
The police fired on the protesters after thousands of them had gathered at a square in the southern port city, Fathi Ben Lazraq, a member of the Southern Movement, told AFP.
A rival rally was held in the same spot by members of the Islamist Al-Islah (reform) party, in support of unity and of President Abdrabuh Mansur Hadi, whose uncontested election ended 33 years of iron-fisted rule under Saleh.
The powerful Southern Movement is demanding independence for south Yemen, and had warned of unrest if Al-Islah went ahead with rival demonstrations.
Eleven southerners were also wounded by the police in clashes around Aden on Thursday, as they tried to prevent thousands of separatists from entering the city from neighboring provinces, according to the group.
Two policeman were wounded by sniper fire from the rooftops of buildings surrounding the protest square, security officials said.
Aden was paralyzed on Thursday as security forces deployed heavily around the city, and with residents fearing the rival rallies would degenerate into violence, an AFP correspondent reported.
Saleh, the former president, was formerly replaced by Hadi 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.
South Yemen was a separate state before unification with the north in 1990. It broke away four years later, sparking a civil war, before it was overrun by northern troops.
Some factions of the Southern Movement want autonomy for the area, but more hardline members are pressing for a return to complete independence for the south where residents complain of discrimination by the Sanaa government.