Thousands of people rallied in south Yemen on Sunday's 19th anniversary of the civil war that was won by the north to demand secession for the south.
"No union and no federation -- no to the occupation!" the crowds chanted in the Hadramawt provincial capital of Mukalla, an AFP correspondent said.
They waved the flag of the former South Yemen and portraits of Hassan Baoum, head of the Southern Movement's supreme council.
In a statement, the protest organisers reaffirmed their rejection of a national dialogue under way in the capital Sanaa.
They demanded "negotiations... under Arab or international patronage, to discuss ways of ending the occupation of the south", it said.
After the former North and South Yemen united in 1990, the south broke away in 1994, triggering a civil war that ended with the region being overrun by northern troops.
Southerners have complained of discrimination and being marginalised ever since.
The national dialogue began on March 18 and is due to last six months.
It brings together 565 representatives from Yemen's various political groups, ranging from the southern secessionists to Zaidi Shiite rebels in the north, as well as civil society representatives.
In Aden, former capital of the south, shops were shuttered and offices closed on Sunday, witnesses said, as southerners marked the anniversary of the end of the war.
Witnesses said youths blocked some main roads with boulders, an action that was repeated in other towns across the south.
The UN-backed national dialogue aims to draft a new constitution and prepare for elections in 2014, after a two-year transition led by President Abdrabuh Mansur Hadi.
It followed a UN-brokered deal that eased former strongman Ali Abdullah Saleh from power after an 11-month uprising against his 33-year rule.