Chad's President Idriss Deby on Friday broke diplomatic ties with neighbour Sudan, which he accused of trying to topple him, and warned that his country could stop sheltering thousands of Sudanese refugees.
He made the announcement at a rally in N'Djamena in which he once again accused the Sudanese government of backing armed groups which have carried out attacks across Chad, including a surprise raid on the capital on Thursday.
"We have taken the decision to break our diplomatic relations with Sudan today and to proceed to close our frontiers," Deby, wearing a dark suit and tinted glasses, told the rally in N'Djamena's Independence Square.
Sudan's government denied it was helping anti-Deby rebels.
"Let me repeat that Sudan is not involved in these Chadian internal affairs. They have a revolt, we are not involved," said Sudanese Foreign Ministry spokesman Jamal Ibrahim.
Next to Deby as he spoke were 160 rebel prisoners and 14 military vehicles he said were captured by his forces when they repulsed Thursday's raid. His government said they revealed Khartoum's backing for anti-Deby opponents.
Deby criticised the international community for being slow to react to the escalating border crisis with Sudan, which is centred on the Sudanese region of Darfur where political and ethnic conflict has raged since 2003.
He said if the international community did not solve the Darfur crisis by June and guarantee security on the border then his country would no longer shelter more than 200,000 Sudanese refugees who have fled the fighting in Sudan's vast west.
"If after June, we can't guarantee the security of our citizens and the refugees, then it is up to the international community to find another country to shelter these refugees," he said.
His warning puts pressure on the United Nations to speed up a solution to Darfur's three year conflict. UN efforts to beef up an African Union peacekeeping force in Darfur with a stronger UN-led force have been delayed by diplomatic wrangling and Sudan's resistance.