Burkina Faso's opposition parties and the African Union have rejected the army's seizure of power in the West African country after the resignation of President Blaise Compaore.
A coalition of opposition parties and civil society groups met late on Saturday and issued a statement in which they described the army takeover a confiscation of people's victory.
"The victory of the popular uprising - and consequently the management of the transition - belongs to the people and should not in any way be confiscated by the army," the coalition of opposition parties and civil society groups said in the statement.
"Our consultation reaffirmed that this transition should be democratic and civilian in character," it said, announcing a demonstration in the vast Place de la Nation for Sunday morning.
The military top brass named Lieutenant Colonel Isaac Zida, deputy commander of the elite presidential guard, as head of state on Saturday.
A power struggle within the armed forces was resolved by sidelining the chief of staff.
One of Africa's long-serving rulers, Compaore stepped down on Friday after two days of mass demonstrations against his attempts to change the constitution to extend his 27 years in power.
At least three people were killed after protesters stormed the parliament building and set it on fire.
On the streets of Ouagadougou, the capital, protesters voiced anger that they had driven out Compaore - who seized power in a 1987 military coup - only to have another soldier imposed on them.
Under Burkina Faso's 1991 constitution, the head of parliament should take office if the president resigns, with a mandate to organise elections within 90 days. However, the army has dissolved the legislature and suspended the constitution.
In a statement issued by military leaders after meeting to appoint Zida to power, they said the form and duration of the transition would be decided in consultation with all sections of society.
Troops loyal to Zida patrolled the quiet streets of Ouagadougou on Saturday.
"This is not a coup d'etat but a popular uprising," Zida, dressed in military fatigues, said in the studio of BF1 television. "I salute the memory of the martyrs of this uprising and bow to the sacrifices made by our people."
Meanwhile, in a strongly worded statement, the African Union called for the military to hand power over to civilian authorities. It said the Peace and Security Council - the arm of the 54-nation bloc that imposes sanctions for violations of democratic process - would discuss the situation on Monday.
"The Chairperson of the [African Union] Commission ... stresses the duty and obligation of the defence and security forces to place themselves at the disposal of the civilian authorities who should lead the transition," read the statement.
The government of neighbouring Ivory Coast said on Saturday that Compaore had arrived there with his family and entourage but did not specify his location.
Military sources said he was staying at a presidential retreat in the coastal resort of Assinie, to the east of the economic capital, Abidjan.