The African Union (AU) has given Burkina Faso’s military a two-week deadline to hand power to a civilian ruler or face sanctions.

The AU said the army had acted unconstitutionally when it took over after President Blaise Compaore was forced to resign on Friday.

The military said a civilian-led transitional government would be established as quickly as possible.

Mr Compaore resigned after mass protests to end his 27-year rule.

On Saturday, the military named Lt.-Col. Isaac Zida, previously second in command of the presidential guard, as the new interim ruler.

A popular revolt led to Mr Compaore’s resignation, but the military takeover was against democracy, said AU official Simeon Oyono Esono, following a meeting of the body's Peace and Security Council in Ethiopia.

The AU will apply sanctions against Burkina Faso if the military fails to give up power within two weeks, Mr Esonohe told Reuters.

The BBC's Emmanuel Igunza in the Ethiopian capital Addis Ababa says the sanctions could include suspension of Burkina Faso’s AU membership and a travel ban on military officials.

The AU’s Peace and Security Council is expected to meet again in two weeks’ time to discuss the crisis, he says.

Lt-Col Zida told diplomats and journalists in Burkina Faso’s capital, Ouagadougou, that the military had no plan to usurp power.

It wanted a transitional government made up of civilians to take office, he said.

The military would play a supporting role, Lt-Col Zida added.

BBC Afrique analyst Lamine Konkodo says many people in Burkina Faso expect Lt-Col Zida to honour his word, and it was now up to politicians and civil society leaders to agree on who will lead a transitional government.

Most businesses were open in Ouagadougou as the city returned to normal for the first time since last week’s protests against Compaore’s rule.

At least one demonstrator was killed on Sunday after soldiers fired shots at the state TV station and barricaded the main square in the capital, Ouagadougou.

Thousands of protesters demanded the military give up power, chanting slogans like: “The soldiers have stolen our revolution”, “Zida get out!” and “Zida is Judas”.

Mr Compaore, who has now fled to Ivory Coast, first seized power in a coup in 1987, and thereafter won four disputed elections.

The protests were triggered by Mr Compaore’s plan to amend the constitution so that he could run for office again in elections next year.

•Credit (except headline): BBC. Photo shows Burkina Faso’s military rulers.