N'DJAMENA -Chad and the Central African Republic (CAR) have called on the United Nations and African Union to investigate an incident at a border post in which at least six Chadian soldiers and three Russians on a military mission to assist CAR were killed.
A delegation from CAR met with Chad's interim President Mahamat Idriss Deby on Tuesday in response to the incident, which has threatened to sour diplomatic relations.
"The two parties have recognised the gravity of the situation and stress the urgency of clarifying the circumstances in which this attack was carried out," their foreign ministers said in a joint statement late on Tuesday.
Chad's defence ministry on Sunday said that Central African troops had attacked a Chadian military post, killed one soldier, and kidnapped and executed five others - actions it said amounted to a war crime.
CAR authorities said a firefight had broken out by mistake as their soldiers pursued a rebel group near the Chadian border, resulting in the deaths of troops on both sides. They did not specify how many Central African soldiers had died.
Russia's RIA news agency reported three Russian soldiers, part of a mission to support CAR's military, were also killed during the operation as a result of a mine explosion.
A spokesman for Chad's army told Reuters on Tuesday that more troops had been deployed to the border in response to the incident.
"We were attacked on our territory by the army of a neighbouring country. So that this kind of thing does not repeat itself, we are obliged to reinforce security at the border," General Azem Bermandoa Agouna said.
Chadian soldiers were central to an African peacekeeping mission deployed to CAR after a rebellion in 2013 that toppled the president. Chad withdrew its forces the following year after they were accused by some in CAR of siding with mainly Muslim rebels in their conflict with mostly Christian militias.