Sudanese protesters rallied again Friday and security forces fired tear gas at them, a day after a mass demonstration drawing tens of thousands was met with the deadliest violence so far this year.

Hundreds of activists massed near the presidential palace in the capital Khartoum, after at least nine people were killed during Thursday's rallies against a military takeover led by army chief Abdel Fattah al-Burhan last October.

"The people want to bring down Burhan," some protesters chanted while others, carrying photos of people killed in months of protest-related violence, yelled: "We call for retribution!"

The death toll from protest-related violence has reached 113 since the coup, with the latest fatality reported Friday after a demonstrator died from wounds sustained at a June 24 rally, according to pro-democracy medics.

Protesters set up barricades and set ablaze car tyres in North Khartoum, while others tried to march on the presidential palace from the centre of the capital, AFP correspondents reported.

The activists demand the restoration of the transition to civilian rule, that was launched shortly after the 2019 ouster of veteran president Omar al-Bashir but which has been derailed since.

The latest crackdown defied calls for calm from the international community.

"Tens of thousands of Sudanese took to the street... to demand democracy. We support their aspirations," said the US State Department's Bureau for African Affairs on Twitter.

"We condemn in the strongest terms the use of live fire by security forces against civilians. We offer our condolences to those who lost family members."

The "violence needs to end", demanded UN special representative Volker Perthes.

The British embassy in Khartoum said it was "appalled" by Thursday's killings and called for a probe.

"Impunity and killing must stop," it said.

Sudan's police accused protesters of wounding 96 police and 129 military officers, "some critically", on Thursday, as well as damaging vehicles and starting fires.

'Excessive force'

Last year's coup plunged Sudan into deepening political and economic turmoil, which has seen rising consumer prices and life-threatening food shortages.

It has also sparked near-weekly protests, as well as ethnic clashes.

The United Nations, the African Union and regional bloc IGAD have tried to facilitate talks between the generals and civilians, but mediation efforts have been boycotted by the main civilian factions.

On Friday, the three bodies jointly condemned the violence and "the use of excessive force by security forces and lack of accountability for such actions, despite repeated commitments by authorities".

Norway's ambassador to Sudan also condemned reports of "torture, sexual violence and inhumane treatment".

"We request lawyers' access to detainees and their access to health," ambassador Therese Loken Gheziel wrote on Twitter. "Protection from torture is indispensable".

The protests on Thursday came on the anniversary of a 1989 coup that toppled Sudan's last elected civilian government and ushered in three decades of iron-fisted rule by Islamist-backed Bashir.

It was also the anniversary of 2019 protests demanding that the generals who had ousted Bashir in a palace coup earlier that year cede power to civilians.

Those protests led to the formation of the civilian-military transitional government that was toppled in last year's coup.