Hundreds of Sudanese protesters demanding an end to military rule took to the streets of the capital Khartoum and its suburbs for a fourth straight day Sunday, witnesses said.

A violent crackdown by security forces during mass rallies on Thursday killed nine people, according to medics, the deadliest day for several months in the long-running protests against a coup last October led by army chief Abdel Fattah al-Burhan.

Recent protests have seen crowds burn tyres and barricade roads with bricks, while security forces have used live bullets, fired barrages of tear gas canisters and deployed powerful water cannons, according to medics and the United Nations.

Demonstrators are demanding a restoration of the transition to civilian rule that was launched after the 2019 ouster of longtime autocrat Omar al-Bashir and which the coup derailed.

"We will continue this sit-in until the coup is overturned, and we have a fully civilian government," demonstrator Muayyad Mohamed told AFP in central Khartoum.

The death toll from protest-related violence has reached 114 since last year's coup. The latest fatality came on Saturday when a demonstrator died from wounds sustained at a June 16 rally, according to pro-democracy medics.

"We will not compromise until the goals of our revolution are realised," said Soha, 25, another protester, who only gave her first name.

"We are here in the street demanding freedom, peace, justice, a civil state and the return of the military to the barracks."

Last year's coup plunged Sudan further into political and economic turmoil that has sent consumer prices spiralling and resulted in life-threatening food shortages.

On Sunday, witnesses reported a heavy deployment of security forces on the streets of Khartoum, including both army vehicles and those of the Rapid Support Forces (RSF), a feared paramilitary unit commanded by Burhan's deputy, Mohamed Hamdan Daglo.

The RSF incorporated members of the Janjaweed militia, which was accused by rights groups of atrocities during the conflict that erupted in 2003 in the western region of Darfur.

More recently, the RSF has been accused of taking part in crackdowns on protesters marching against military rule.