Chad's President Idriss Deby has called on the African Union to move next month's summit from Sudan to Nigeria.
Chad says last week's attack was launched from Sudan
He has accused Sudan of being behind a rebel group who last week attacked the border town of Adre killing 100 people.
But Sudan's foreign minister told the BBC that Sudan's army had fought against Chadian rebels when they refused to disarm or leave Sudan.
Correspondents say the rebels are led by Chadian soldiers who have mutinied against President Deby.
Mr Deby made the comments after talks near Lagos with Nigeria's President Olusegun Obasanjo, who is the current AU chairman, and asked the AU to condemn Sudan.
"An aggressive neighbour like Sudan is not capable of hosting the next AU summit, not to mention being the next chairman," Mr Deby said, Reuters reports.
"I came to complain to the current AU chairman about the continued Sudanese aggression towards Chad," he said
Last week Chad said it was in a "state of war" with Sudan after the attack which Sudan vigorously denies any involvement in.
Chad says that Sudan is backing rebel groups which have recently sprung up in the east of the country and which are blamed for the attack on Adre, which borders Sudan's troubled Darfur region.
It also accuses Sudanese militia of making daily incursions into Chad, stealing cattle, killing innocent people and burning villages on the Chadian border.
The Chad rebels want to oust Idriss Deby's government
"Of course it is not true that Khartoum is trying to destabilise Chad," Sudanese Foreign Minister Lam Akol told the BBC's Focus on Africa programme.
After Chadian rebels crossed into Sudanese territory and refused to disarm, the Sudanese army fought with them, he said.
"This goes a long way to prove that there is no problem being caused to Chad with our border. If they [the rebels] are causing problems within Chad then that is an internal problem and we have nothing to do with it, " he said.
In the past few days the AU has sent a delegation to N'Djamena and Khartoum as part of efforts to reduce the tension between the two countries.
Sudanese President Omar al-Bashir is due to take over the chairmanship of the AU from Mr Obasanjo next month.
On Sunday, the Organisation of the Islamic Conference urged Sudan and Chad to exercise self-restraint to defuse the growing tensions.