French photojournalist Camille Lepage on assignment in the Central African Republic in February. Lepage, 26, was found dead on Tuesday, having been shot during a firefight. Fred Dufour / Agence France-Presse

The UN Security Council has condemned the killing of a French journalist in the Central African Republic and stated those responsible "shall be held accountable".

The body of 26-year-old Camille Lepage, described by her mother in French media as "an exceptional girl" who wanted to be "a witness to people that are not talked about and who are in danger", was found on Tuesday by a patrol of French peacekeeping troops.

They found the journalist's body in a vehicle driven by "anti-balaka" militiamen in the region of Bouar, in the west of the CAR, a French presidency statement said.

French President Francois Hollande, speaking earlier during a visit to the Georgian capital of Tbilisi, said Lepage "was taking photographs, doing her job and no doubt fell into an ambush".

A French military source said Lepage was with the militia as part of her efforts to report on the conflict when they were attacked on Monday.

"She was killed by gunfire and her body was recovered by the anti-balaka, along with those of their comrades," said the source, who requested anonymity, adding that an inquiry was underway into the exact circumstances of her death.

Lepage worked as a photographer for Hans Lucas, a studio based in Paris, according to its website.

Conflict in CAR

The deeply impoverished CAR has been gripped by crisis since the mainly Muslim Seleka rebels seized power in a March 2013 coup, but were then replaced with an interim government in January.

Splinter groups of Seleka rebels embarked on a campaign of killing, raping and looting, prompting members of the Christian majority to form vigilante "anti-balaka" groups.

The two groups have unleashed a wave of tit-for-tat killings that has left thousands dead and close to a million displaced.

Lepage's mother said her daughter left for the CAR in September, adding: "She wasn't afraid."

The UN Security Council members sent their condolences to the victim's family and underlined that, according to international humanitarian law, journalists in a conflict zone should be treated as civilians.

The Security Council statement called on the CAR government to investigate the incident, and stressed that "those responsible for the killing shall be held accountable".

Sanctions imposed

On Tuesday, US President Barack Obama imposed sanctions against former CAR leaders Francois Bozize and Michel Djotodia and three other officials, the White House said.

The move comes on the heels of UN sanctions announced on Friday by the Security Council against three of the same five men, including Bozize.

Obama has also put in place a framework for potentially wider sanctions, calling the situation in the CAR a "threat to the national security and foreign policy of the United States" in a letter to Congress.

Hollande said that French troops along with European and African forces must continue their work to help restore peace and stability in the conflict-torn country.