Yemen's separatist Southern Movement called for "a day of rage" on Wednesday in the tightly patrolled city of Aden to mark the 16th anniversary of the invasion of the south by northern forces.
The Supreme Council for the Peaceful Movement to Liberate the South issued a statement on Monday calling on all southerners to "make Wednesday a day of rage" to express "our people's determination to continue their peaceful struggle until liberation and independence."
The group also appealed to southerners to participate in the funeral of a fellow townsman, Ahmed Mohammed Darwish, who died last Friday in a prison in Aden, the capital of formerly independent South Yemen.
Darwish was "killed by Sanaa's occupying regime inside a prison cell," the statement said.
He had died a day after he was detained along with dozens of others, following a suspected Al-Qaeda attack in the city's intelligence headquarters on June 19.
Eleven people including seven military personnel were killed in the attack, officials had said.
Two other groups from the Southern Movement, the National Council for the Liberation of the South and the Union of Youth of the South, also called for a general strike in seven southern provinces on Wednesday, but did not mention Aden.
The Yemeni army has been present in large numbers in Aden, to prevent the kind of protests and unrest seen in other southern cities.
The Southern Movement is a coalition of groups with a range of demands from economic and social improvements to full independence for the regions of former South Yemen.
The impoverished country's south was independent from 1967 until 1990 when it united with the north. The south seceded in 1994, sparking a short-lived conflict that ended when the south was overrun by northern troops.