Yemeni President Abedrabbo Mansour Hadi, who resigned last month under pressure from Shiite militia, left Sanaa on Saturday after weeks under effective house arrest, an aide told AFP.
Hadi arrived in the main southern city of Aden, where his supporters have refused to recognise the authority of the presidential council installed by the Huthi militia to replace him.
He travelled overland in a convoy of dozens of vehicles, passing through third city Taiz, which like Aden is outside Huthi control.
"He managed to leave his house this morning and his way is being secured to reach Aden," the aide said earlier.
A top security official in Aden told AFP that Hadi was staying in a presidential residence in the Khormaksar diplomatic district of the southern port city.
It was not immediately clear whether the Huthis had allowed him to leave in the face of demands by the UN Security Council for an immediate end to his house arrest.
The aide insisted that Hadi left "without an arrangement or even informing any of the political parties."
The Huthi militiamen, whose power base is in Yemen's mainly Shiite northern highlands, overran the capital unopposed in September.
Last month, they seized the presidential palace and laid siege to Hadi's residence, prompting him to tender his resignation.
The Huthis have pushed their advance into mainly Sunni areas south and west of Sanaa, where they have met with fierce resistance from armed tribesmen and Al-Qaeda militants.
But Taiz and some other parts of the north, as well as the whole of the south, remain beyond the militia's control.