ADEN - Yemeni authorities have freed a leading southern separatist days after he was arrested on his arrival in Aden after spending several years in self-imposed exile, an official told AFP on Sunday.

Former ambassador Ahmed al-Hassani, who has lived in Britain since 2006 as a political refugee, was arrested at dawn on Wednesday at the airport after arriving on-board a flight from Beirut. Hassani was freed overnight Saturday on the express orders of President Abdrabuh Mansur Hadi, the official said.

Hassani is the secretary general of the Southern Democratic Assembly. Yemen's southern separatists have for decades complained of marginalisation by Sanaa. Though the movement remains fractured, it demands autonomy and in some cases independence.

South Yemen was a separate nation before unification with the north in 1990.