Under international pressure to quell domestic unrest and focus its sights on eradicating the presence of al-Qaeda in the country, Yemen earlier this week offered to hold talks with southern separatists and hear their grievances.
While offering dialogue, Ali Abdullah Saleh, the Yemeni president, also said the separatist flag would "burn in the days and weeks ahead".
The separatists, who lack a unified leadership, have given no public response to the president's offer.
Meanwhile demonstrations were being held in several cities, with crowds calling for the military to withdraw from southern cities and for the government to halt a sweeping campaign of arrests.
Thousands took to the streets of the northern city of Taiz, answering a call by the opposition coalition to protest against "the militarisation of southern provinces," and demonstrate "solidarity with the demands of the Southern Movement," according to banners raised by protesters.
A peaceful protest was also organised in the capital, Sanaa, where some 5,000 opposition supporters demonstrated.
The opposition coalition, which includes both northern and southern groups, calls for the social and economic demands of the south to be met, but stops short of backing renewed independence, which is now overtly championed by some members of the Southern Movement.
A coalition statement released on Thursday called "for rapid national action to support and defend the oppressed".
It described the developments in southern Yemen as "dangerous" saying it "resulted from the dangerous escalation that the authorities resorted to through intensifying the use of force, arrests and hunting" of activists.
Some 250 southern activists have been arrested this week in the clampdown,
an officials said, speaking on condition of anonymity because they were not
authorised to speak to the media.
The statement stressed the coalition's position of "standing by the just demands of the people in the southern provinces to remove all the marks of the 1994 war."
South Yemen was independent from 1967 until it united with the north in 1990. An attempt to break away again in 1994 sparked a short-lived civil war that ended when the south was overrun by northern troops.