Chad on Saturday accused Sudan's air force of bombing four towns along its eastern frontier, but Khartoum dismissed the allegation as propaganda aimed at undermining an uneasy peace between the two neighbours.
Chadian President Idriss Deby's government said Sudan bombed the towns of Bahai, Tine, Karyari and Bamina on Friday, destroying homes and sowing panic among residents. It did not give any information on casualties.
"The government expects the African Union ... and the United Nations to condemn this bombardment of peaceful Chadian citizens and for them to work to stop the repeated Sudanese attacks against Chad," a statement from the government spokesman Hourmadji Moussa Doumgor said.
"In the face of this escalation of Sudanese aggression, all necessary steps have been taken to permit security and defence forces to carry out their responsibilities," he added. The incident came only days after Chad accused Sudan of backing an incursion this week by a heavily armed rebel convoy deep into its territory.
In April, Deby broke off diplomatic ties with Khartoum, saying it had backed another lightning rebel raid which reached the capital, N'Djamena, where hundreds were killed in fighting.
Sudan, which accuses Chad of supporting rebels in its strife-torn Darfur region, denied its air force had taken part in any operation which would violate a deal in August to restore diplomatic relations after months of tension.
The United Nations is considering a possible peacekeeping force in eastern Chad where the spillover from violence in Darfur has resulted in more than 200,000 refugees, its top peacekeeping official said on Friday.
Khartoum has resisted pressure to allow UN peacekeepers into Darfur itself, where roughly 200,000 people have been killed and more than 2.5 million displaced since fighting flared in 2003 between rebels, government forces and militias.