At least two people in Yemen have been killed at a protest in the southern port city of Aden.
Witnesses said security forces opened fire on the crowd but a local official told the official news agency Saba that "criminal elements" had opened fire.
At least 15 people were injured at the rally to call for reconciliation between the north and south of Yemen.
There have been tensions since the two parts merged in 1990 under a northern-dominated government.
Some of the demonstrators called for the south of Yemen to split from the north.
Southerners complain that the north is economically more developed and that northerners are favoured by the national government in the northern capital of Sanaa.
Former army members in the south have taken the lead in demanding political reforms in Yemen - one of the poorest countries in the world.
Thousands of soldiers from the south left the army and fled abroad after a civil war in 1994 which was won by northern forces under President Ali Abdallah Saleh.
Many have since returned, but complain that the government has reneged on promises to allow them to rejoin the northern-dominated army.