The army deposed elected president Alpha Conde following months of brewing discontent.

Coup leader Colonel Mamady Doumbouya -- who was later declared interim president -- has promised to restore civilian rule but has so far refused to commit to a date, in defiance of international pressure to do so.

In a joint statement, the Economic Community of West African States (ECOWAS) and the UN said Thursday they were "especially concerned" about the lack of a timetable for returning to democratic rule.

They urged the junta to draw up an "acceptable timetable" as soon as possible.

The call followed a visit from a joint ECOWAS-UN delegation to Guinea this week for talks with the junta.

ECOWAS had also earlier urged Guinea to stage elections within six months of taking power.

"The delegation noted the failure to comply with the six-month deadline," the statement said.

Guinea's coup has fuelled concerns about democratic backsliding across West Africa.

The impoverished nation of 13 million people is one of three countries in the region where the military seized power in the space of just 18 months, along with Mali and Burkina Faso.

ECOWAS has suspended all three countries from the bloc's activities over the coups.

On Tuesday, an influential Guinean democracy group warned it would organise mass protests unless the junta cedes power swiftly.