The Sudanese army has surrounded presidential palace in the capital Khartoum following months of protests against Hassan Omar al-Bashir's rule.
There is speculation that a coup attempt could be underway against President al-Bashir, with the State radio reporting that the army is set to make an "important" announcement soon.
"The Sudanese army will issue an important statement soon. Wait for it," a television anchor said, without giving further details.
The brief media report, accompanied by patriotic music, was made as protesters marked their sixth straight night vigil outside the military headquarters in Khartoum.
Witnesses told the Reuters news agency that thousands of people had descended on the country's defence ministry chanting, "It has fallen, we have won."
Several military vehicles carrying troops entered the army compound in the early hours of Thursday, witnesses told AFP.
The compound also houses Bashir's official residence and the defence ministry.
A protester told Chanel 4 News Correspondent Yousra Elbagir that thousands were already heading towards the sit-in outside the military nerve centre, where many are already in a celebratory mood.
"We won't be leaving the sit-in until those who have been detained are released and there is justice for those killed."
On Thursday, Yousra also tweeted that there were unconfirmed reports that senior government officials had been arrested, and Khartoum International Airport shut.
The Bloomberg reported that al-Bashir plans to step down, quoting Arabiya news agency.
The report cited unidentified sources within the military.
If al-Bashir steps down, he will be the second leader in North Africa to bow down to nationwide protests in April after Algerian President Abdelaziz Bouteflika was forced to resign.
The wave of unrest against the autocratic president started in December after the government hiked the price of a loaf of bread from one Sudanese pound to three (from about $2 cents to $6 cents).
As early as in December, the protesters gathered in markets chanting the slogan "the people want the fall of the regime."
Mr al-Bashir, who is currently wanted by the International Criminal Court for alleged crimes against humanity and genocide, seized power in a military coup in 1989.
He briefly hosted slain terrorist Osama bin Laden in the 1990s.
Bin Laden planned and executed the deadly US embassy bombings in Nairobi and Dar es Salaam in 1998.
He was killed by US special forces on May 2, 2011 in Abbottabad in Pakistan.