Yemen's main southern opposition leader, Hassan Baoum, was released from jail along with his son just hours after the formation of a transitional unity government, a family member told AFP in Sanaa.
Baoum and his son Fawaz were arrested on February 20 in Yemen's southern port city Aden, where they had planned to join an anti-government protest. They were freed late on Wednesday.
"My father and brother Fawaz were both released in Sanaa," said Fadi Baoum, another son of the southern opposition leader.
Baoum heads the supreme council of the Southern Movement whose members call for either independence or increased autonomy from north Yemen.
He has been arrested on several occasions by the central government.
Baoum's release came just hours after Prime Minister-designate Mohamed Basindawa, a southerner himself, announced the formation of a transitional unity government that will lead Yemen until February, when Vice President Abdrabuh Mansur Hadi is formerly elected to the presidency.
Hadi, another southerner, was given temporary presidential powers and asked to form a unity government after President Ali Abdullah Saleh signed a Gulf-sponsored initiative aimed at ensuring a smooth transition of power in Yemen after months of mass anti-government protests.
In return for stepping down, Saleh and his family were granted immunity from prosecution for alleged crimes committed against Yemenis in the protests that began in January demanding his ouster.
Hundreds have been killed and thousands more wounded in the capital and other Yemeni cities in a brutal government crackdown on demonstrations.
The Gulf Cooperation Council initiative also calls on the new Yemeni leadership to ensure a peaceful and just resolution of the southern issue.
Residents in the formerly independent southern region complain of discrimination by the Sanaa government in the distribution of resources since the union between north and south in 1990.
The south broke away again in 1994, sparking a brief civil war that ended with the region overrun by northern troops.