Sudan’s armed forces are set to deliver an “important statement” after senior officials said the military had forced long-time President Omar al-Bashir to step down.
The circumstances of his apparent removal and his current whereabouts remained unclear.
State TV said an army statement was imminent amid swirling reports of a coup to replace the president of 30 years following mass street protests against his rule.
The announcement raised expectations that Mr al-Bashir was relinquishing power or was being removed by the military.
Two officials, who hold high positions in the government and the military, said the army was in talks about forming a transitional government.
Pan-Arab TV networks also carried unconfirmed reports that Mr al-Bashir had stepped down and that senior ruling party officials were being arrested.
They aired footage of masses heading towards the presidential palace in the capital Khartoum, waving the national flag, chanting and clapping.
Mr al-Bashir, who is a pariah in many countries, is also wanted by the international war crimes tribunal for atrocities in Darfur.
Witnesses in Khartoum said the military had deployed at key sites in the city to secure several installations.
Armoured vehicles and tanks are parked in the streets and near bridges over the Nile River, they said, as well as in the vicinity of the military headquarters, where thousands were awaiting the army statement.
Organisers of the protests urged crowds to converge and join a sit-in under way in Khartoum since the weekend. They issued a statement vowing to remain in the streets until the “regime steps down completely and power is handed to a civilian transitional government”.
There were also unconfirmed reports that the airport in the Sudanese capital had been closed.
Ahead of the expected army statement, Sudanese radio played military marches and patriotic music. State TV ceased regular broadcasts, with only a brief announcement saying there will be an “important statement from the armed forces after a while, wait for it”.
The development followed deadly clashes between Sudanese security forces and protesters holding a large anti-government sit-in outside the military’s headquarters in Khartoum, which also include a presidential residence.
There were several attempts to break up the sit-in, leaving 22 dead since Saturday.