Sudan accuses Chad of third air strike

* Sudan says Chad bombed its territory for third time

* Sudan signals it may consider political solution (Updates with reaction from Chad, U.N.)

KHARTOUM, May 16 (Reuters) - Sudan accused its neighbour Chad of a third air strike on its territory on Saturday and signalled it might be open to a political solution to the growing conflict.

"There was another air strike this morning at around 10 a.m.," said Ali Youssef Ahmed, head of protocol at Sudan's Foreign Ministry. "This aggression continues (and) this makes the situation graver," he added.

Sudan accused Chad on Friday of launching two bombing raids on its territory, saying they constituted an "act of war". Chad has said Sudan sent rebel forces over its border earlier this month, raising fears of the collapse of a recent peace deal.

Relations between the two countries have become entangled in Sudan's festering Darfur conflict and each country has accused the other of supporting rebels inside its borders.

A Chad government spokesman did not explicitly confirm the raids but reaffirmed what N'Djamena sees as a right to deal with attacks from insurgents within Sudan's borders.

"That is the logical consequence of the rebel attacks. We pursued them into Sudanese territory," government spokesman Mahamat Hissene said.

Brigadier Uthman al-Agbash, spokesman for Sudan's armed forces, told reporters on Saturday he was still waiting for a signal from the government on how to respond to the attacks. He suggested that the authorities might be seeking a diplomatic solution.

"This incident is tied up with political, social and economic issues and will not be solved by a military option," he said, adding that no one was injured in the three air strikes.

Agbash added he thought a third nation may have supported Chad in the attack, a possible reference to France which Sudan accuses of backing the N'Djamena government.

"These (raids) are beyond Chad's capability and that means Chad was not alone," he said.

Ali Youssef Ahmed of the Sudanese foreign ministry told Reuters that Sudan had not ruled any options out when it came to responding to the attacks.

But he said Sudan had already stepped up diplomatic activity since the air strikes and was consulting neighbours including Ethiopia.

High-level discussions were going on with the African Union and Senegal, which has acted as a peace broker between Sudan and Chad in the past, had sent a delegation to Khartoum, he said.

U.N. officials based in Chad and Sudan said they had not been able to confirm the raids themselves. The joint U.N./African Union UNAMID peacekeeping mission in Sudan's Darfur region said it was planning to send an investigation patrol to the area later on Saturday.

"We are following the situation very closely and have reinforced our patrols in the east of the country (Chad)," said Penangnini Toure, spokesman for the United Nations mission in Chad (MINURCAT) by telephone. (Additional reporting by Mark John in Dakar and Moumine Mgarmbassa in N'Djamena)