At least 16 people were injured when separatists attacked pro-reform activists in the southern Yemeni city of Aden, a local news website reported Sunday.
Hundreds from the Southern Movement, which is pushing for the separation of southern Yemen, late Saturday torched tents pitched by the activists in the Freedom Square in Aden, according to Mareb Press, DPA reported.
The violence comes less than two weeks before an early presidential election in the impoverished Arabian Peninsula that has been gripped by a year of unrest.
"The assailants used petrol bombs in torching the tents while some activists were inside them," Mareb Press quoted Ali Qassem, the head of the city's Revolution Organization, as saying.
The separatists in southern Yemen are calling for boycotting the presidential election set for February 21.
At least four people have been killed in southern Yemen over the past week in clashes between supporters and opponents of the polls, according to local media reports.
In November, President Ali Abdullah Saleh signed a United Nations-backed deal to step down after 33 years in power, in return for immunity from prosecution.
The parliament unanimously nominated Vice President Abd Rabbu Mansur Hadi as the sole presidential candidate for the polls.