Sudanese protesters rally near the military headquarters during a demonstration in the capital Khartoum. [Courtesy]

Sudan’s ruling military council has indicated that the transition period it announced on Thursday to be two years at most can be as short as one month if it is managed “without chaos.

The head of the transitional military council, Defence Minister Mohammed Ahmed Awad Ibn Auf said on Thursday when announcing the overthrow of Omar al-Bashir that the council would lead a two-year transition before holding elections.

While addressing a news conference in the capital, Khartoum on Firday, Omar Zein Abideen, who heads the military council's political committee said that the army has "no ambition to hold the reins of power", and stressed that "we are ready to step down as early as a month if a government is formed".

"We guarantee the new government will be run by the civilians without the military," he said.

He added that the military acted to remove President Omar al-Bashir to meet the demands of the people and called for "civilised and peaceful dialogue" to address the economic and political issues facing the country.

"The committee plans to begin dialogue with political groups later. We are the protectors of the demands of the people and that is by consensus from the political entities," Abideen said.

Organisers of the months-long demonstrations that triggered the overthrow of Sudan's President Omar al-Bashir have urged pro-democracy supporters to protest against a military takeover, renewing their demands for a civilian-led government.

The appeal by the Sudanese Professionals Association (SPA) came late on Thursday as tens of thousands of protesters defied a nighttime curfew announced earlier in the day by General Awad Ibn Auf, who was sworn in as the head of a military council that replaced al-Bashir.

In a Twitter post, the SPA called on protesters to "gather now" and continue a days-long sit-in outside the army headquarters in the capital, Khartoum.

"Stay put and guard your revolution," it added. "To comply with the curfew is to recognise the clone rescue government."

The Central Committee of Sudanese Doctors said that at least 13 people were killed when security forces intervened in Thursday's protests.

They included two demonstrators in the capital Khartoum, the Committee said in a statement on Friday.

Since Saturday, at least 35 people have been killed in clashes with security forces, which have repeatedly tried to disperse the sit-in by force, it added.