N'DJAMENA: An attack that killed six Chadian soldiers at a border post with the Central African Republic will be jointly investigated by the two countries, after a high-level meeting Tuesday appeared to ease tensions.

Chad has blamed the CAR army for the attack, and says five of the soldiers were abducted then executed in the incident on Sunday, which it labelled a "war crime" that would "not go unpunished".

CAR had put the blame on rebels it said its soldiers had been pursuing.

At the meeting between the two states' foreign ministers, "the CAR side, after expressing surprise at the attack, firmly condemned it and expressed its profound sympathy to the government and people of Chad", a joint statement released afterwards said.

The two parties "underlined the urgency of clarifying the circumstances in which this attack took place" and agreed to set up an independent international commission of inquiry.

The two sides also agreed to work together to strengthen security along the border.

Earlier the mood was more tense, with Chadian government spokesman Abderaman Koulamallah telling AFP that the attacks were premeditated and that the Central African authorities must "accept and admit their errors".

He had said Chad would press for an international investigation, adding: "depending on what these emissaries tell us, we will see what we can do".

The three CAR ministers carried a letter from President Faustin Archange Touadera, spokesman of the CAR presidency Albert Yaloke Mokpeme told AFP.

The team are due to meet Chad's junta leader, Mahamat Idriss Deby, on Wednesday.

The incident has placed the spotlight on the occasionally fraught relations between Chad -- ruled by a junta that took power just six weeks ago -- and the CAR, an unstable country battling powerful armed groups.

CAR regularly accuses its northern neighbour of supporting armed rebel groups from inside Chad.