OUAGADOUGOU (AFP) - Burkina Faso's opposition and civil society leaders warned on Saturday against a military takeover and called a mass rally after the army stepped into the power vacuum left by the ouster of president Blaise Compaore.

The military named a high-ranking officer, Isaac Zida, to lead the country's transition a day after Compaore was forced to resign as his plans to extend his 27-year rule exploded into violent protests that saw parliament set ablaze.

The protests have led some observers to draw a parallel with the Arab Spring, and were closely watched across a continent where other veteran heads of state are also trying to cling to power.

Zida, who beat out a rival claim by the landlocked west African nation's army chief to fill the post, vowed to work closely with civil society.

But opposition and civil society leaders swiftly issued a statement warning the military against a power snatch, demanding instead a "democratic and civilian transition".

"The victory born from this popular uprising belongs to the people, and the task of managing the transition falls by right to the people. In no case can it be confiscated by the army," they said in a statement.

They also called a new mass rally in capital Ouagadougou on Sunday at the site where up to a million people had gathered earlier this week to demand Compaore's resignation.

The civil society's call appeared to be backed by the African Union, which urged a "civilian-led and consensual transition" in the former French colony.

Zida, the second in command of the presidential guard, said he had assumed "the responsibilities of head of the transition and of head of state" to ensure a "smooth democratic transition".

The transition will be carried out "together with the other components of national life," he said, referring to the political opposition and civil leaders.

The army's endorsement was signed by General Nabere Honore Traore, who initially said he would himself assume power, a claim Zida had dismissed as "obsolete".

Hours after taking over, Zida reopened the country's air space, but land borders remained closed, a statement said.

"The aspirations for democratic change" of the Burkina youth "will be neither betrayed, nor disappointed", he said.

Speaking on television early on Saturday, the military officer also said the ousted president was "in a safe place" and his "safety and well-being are assured".

In neighbouring Ivory Coast the presidency confirmed reports that Compaore, who left Ouagadougou on Friday according to French diplomats, was in the country.

A local resident said he saw a motorcade of around 30 cars heading for a luxury hotel in the Ivorian capital, which is also used as a semi-official residence for foreign dignitaries.

"The services of the President hotel in Yamoussoukro served him (Compaore) dinner yesterday (Friday) and breakfast this morning (Saturday)," according to a hotel employee.

In the Burkina Faso capital, calm returned to the streets, with shops reopening and calls by protest organisers for a cleanup of the debris left behind after violent mass protests.

The uprising was sparked by plans to change the constitution to allow Compaore to stand once again for elections next year.

Defying dramatic protests which drew tens of thousands of people, Compaore initially rejected calls to resign.

He eventually withdrew plans for a vote on the constitutional changes but vowed to stay in power for another year, before announcing on Friday that he was stepping down.

Later the same day, army chief Traore said he was assuming power, after ordering the dissolution of the government and a dusk-to-dawn curfew.

But many protesters were deeply opposed to Traore, seeing him as a close ally of Compaore.

"We do not want General Traore in power. We need someone credible. Traore is Blaise Compaore's henchman," said Monou Tapsoaba, an activist with the opposition People's Movement for Progress.

France's President Francois Hollande vowed that Paris would "contribute to calming" the situation in Burkina Faso, while Washington urged "a transfer of power in accordance with the constitution".

The EU called for the people of Burkina Faso to have the final say in who rules their country.

Compaore was only 36 when he seized power in a 1987 coup in which his former friend Thomas Sankara was ousted and assassinated.

His bid to hold on to power particularly angered young people in a country where 60 percent of the population of almost 17 million is under 25.

Many have grown up under the leadership of one man and are disillusioned by the establishment that has led a country which is languishing near the bottom of the UN human development index.

Known in colonial times as Upper Volta, the country won independence from France in 1960 and its name was changed to Burkina Faso ("the land of upright men") in 1984.