Sudan today accused its neighbour Chad of launching two bombing raids on its territory, describing the attacks as "an act of war".
The accusation comes a week after Chad said Sudan sent rebel forces over its border, raising fears of the collapse of a recent peace deal.
No one was immediately available to comment on the accusation from Chad's government.
"They attacked. They bombed and there were casualties," said Ali Youssef Ahmed, head of protocol at Sudan's Foreign Ministry.
"This was an act of war from Chad. The Sudanese leadership and the Sudanese army are assessing the situation. Sudan has the right to defend its territory."
He declined to comment on whether Sudan planned to retaliate in any way, adding "We are considering all options."
Both countries have regularly accused each other of backing insurgents bent on overthrowing their respective governments.
Ahmed said Sudan's Foreign Ministry had called in Chad's ambassador to demand an explanation for the two sorties and had informed the Khartoum-based ambassadors of the five permanent members of the UN Security Council.
"Three war planes have crossed the borders to an area south of El Geneina (capital of Sudan's West Darfur state) which is 60 km inside Sudanese territory," Ahmed said earlier.
"It happened at 10:30 a.m. and 1:30 p.m. ... It is a violation of our territorial sovereignty. Sudan is in a position to defend its territory," Ahmed said.
Chad accused Sudan of backing a rebel incursion into its territory last week, just days after the two countries signed a pact in Doha in which they agreed to normalise relations and reject any support for rebel groups hostile to either of them.
Chad said it stopped the advance, after clashes that killed 125 rebels. Sudan denied involvement in the raid saying it was a confrontation between Chad's government and "opposition groups".
Chad and Sudan resumed shaky diplomatic ties in November after cutting them in May 2008.
Khartoum had accused Chadian President Idriss Deby of involvement in an attack on the Sudanese capital by Darfur rebels on May 11, 2008.
Reuters