A UN envoy called Sunday for a civilian transition in Burkina Faso after the ouster of president Blaise Compaore, threatening sanctions if the military holds on to power in the west African country.

A UN envoy called Sunday for a civilian transition in Burkina Faso after the ouster of president Blaise Compaore, threatening sanctions if the military holds on to power in the west African country.

"We hope there will be a transition led by a civilian and in keeping with the constitutional order," the UN envoy for west Africa, Mohamed Ibn Chambas, told a news conference. "If not, the consequences are pretty clear. We want to avoid having to impose sanctions on Burkina Faso."

The military named a high-ranking officer, Isaac Zida, to lead the country's transition on Saturday. A day earlier, Compaore was forced to resign as plans to extend his 27-year rule exploded into violent demonstrations that saw parliament set ablaze and hundreds of thousands take to the streets.

Chambas was speaking on behalf of a tripartite group of mediators that included representatives of the African Union and the Economic Community of West African States, after they met with 49-year-old Zida and top military brass.

They "assured us that they had well understood the message," Chambas said.

Zida, who beat out a rival claim by the landlocked nation's army chief to lead the transitional government, vowed to work closely with civil society.

Under the constitution, the speaker of parliament should serve as transitional leader.

Opposition and activist leaders swiftly issued a statement warning the military against a power grab, demanding instead a "democratic and civilian transition".

They called a new mass rally in the capital Ouagadougou on Sunday at the site now nicknamed "Revolution Square".