Chadian President Idriss Deby has accused the EU protection force in eastern Chad of closing its eyes to the killing of civilians and refugees by advancing anti-government rebels.
Mr Deby said 'We have the right to ask ourselves about the effectiveness of such a force, of the usefulness of its presence in Chad.'
He added that an international plot sought to plunge his country into civil war.
Minister for Defence Willie O'Dea is on a three-day visit to Chad despite shooting incidents involving Irish troops on Saturday.
No Irish soldiers were injured in the weekend clashes and the minister decided to go ahead with his visit even though the situation in the area where the Irish are stationed is described as calm but tense.
The full battalion of 400 Irish soldiers took up position in Chad in the past few weeks.
It is not clear who shot at the Irish troops, but they returned warning fire from their armoured vehicle and no-one was injured.
Since then rebels have moved out of the area and the Defence Minister and Chief of Staff Lieutenant General Dermot Earley decided to push ahead with their visit.
They will arrive in the capital, N'Djamena, this evening and hold talks with the Chadian Defence Minister.
They will travel southeast to Camp Ciara near the town of Goz Beida tomorrow where the Irish troops are stationed.
Mr O'Dea said the troops are working under extremely harsh and dangerous conditions in difficult terrain.
They will meet the troops and hold talks with aid workers about the humanitarian situation in the refugee camps where people who have escaped from the violence in Darfur are living.
