CAIRO — Power-sharing talks in Sudan between the ruling military junta and the leaders of a powerful protest movement collapsed on Wednesday after violent clashes erupted in the capital, Khartoum, for the second time this week.

The leader of the ruling Military Transitional Council, Lt. Gen. Abdel Fattah al-Burhan, said in a televised address that the talks, which only hours earlier appeared to be going well, would be suspended for 72 hours. He laid down several conditions for a resumption of negotiations.

The announcement came hours after security officials opened fire on protesters, apparently in an attempt to clear checkpoints from the city center, wounding at least nine people and leading to recriminations on both sides.

The events marked another turbulent day in the political crisis that has enveloped Sudan since last month’s ouster of President Omar Hassan al-Bashir.