The UN envoy to the Central African Republic has urged the country to “make an example” of soldiers who lynched a man accused of being a rebel yesterday.
The man was stabbed and beaten to death and then his body burned in the capital, Bangui.
It happened just moments after interim President Catherine Samba-Panza finished speaking at an army ceremony.
Separately, France says its peacekeeping forces are now likely to stay for longer than six months.
The lynching is the latest in a series of shocking acts in CAR which have continued despite the resignation of a former rebel who seized power last year.
Much of the violence has been along religious lines, between minority Muslims and Christian groups.
UN envoy Babacar Gaye said the killing of the man was “unacceptable” and “must be properly investigated and the culprits punished and made an example of”.
The man was killed in view of several photographers and as African Union peacekeepers looked on.
The soldiers suspected him of being part of the mainly Muslim Seleka rebels.
Meanwhile, French Defence Minister Jean-Yves Le Drians says his country’s peacekeeping forces are likely to stay in CAR for more than the initial six months.
The UN Security Council authorised French and African troops to intervene in the country last December.
On Wednesday, Human Rights Watch has warned that Seleka fighters who fled the capital Bangui have regrouped in the north-east and begun attacks on civilians.
The militants were engaging in “a new wave of horrific attacks against civilians”, the charity said. It added that in some cases Seleka were being helped by Chadian peacekeepers.
Thousands of people have been killed in since Seleka rebels overthrew President Francois Bozize last March.
The violence between the mostly Muslim rebel group and Christian militias – widely knows as anti-balaka (anti-machete) – has continued even though President Samba-Panza was inaugurated last month and Seleka leader Michel Djotodia resigned as president.
Eyewitnesses in Bangui said a crowd accused the man of being a Seleka member, before members of the Central African Armed Forces (Faca) stabbed and kicked him and pelted him with stones.
The victim’s body was dragged on the streets in Bangui and then set on fire
“They proceeded to mutilate his body and then set the body on fire,” Peter Bouckaert, Human Rights Watch’s emergencies director, who was at the scene, told the BBC.
Mr Bouckaert said that as he was taking pictures to document what he described as a “crime”, a group of uniformed soldiers “rushed to the body to pose smiling with the burning corpse in front of us”.
A French contingent later arrived and fired warning shots in the air to disperse the crowd.
Seleka rebels are blamed for a series of deadly attacks on Christians in the country in the past year.
There have also been widespread reports of revenge attacks since the rebels withdrew from Bangui in January.
France, the former colonial power, has 1,600 troops in the country, working with some 4,000 troops from African countries to help end the violence which has seen about a million people – 20% of the population – flee their homes.
In December, the UN said it believed at least 10,000 troops may be required in any force sent to end the unrest.