"We are demonstrating today to tell our sons and daughters that they are not alone," Faiza Hussein, one of the protesters, told AFP.

She added that they are also calling on the authorities to "stop killing our children".

At least 83 people have been killed and thousands injured in unrest that has gripped the country since an October 25 military coup led by General Abdel Fattah al-Burhan, according to independent medics.

"We are here to support the youth in their revolution, and to demand an end to the killings," said Hassan Ali, 63.

A United Nations expert on Thursday urged Sudanese forces to stop firing live ammunition and tear gas canisters at protesters.

"Firing live ammunition on the people is a huge violation against human rights," said UN expert Adama Dieng during a visit to Khartoum.

Sudanese authorities have said they arrested several police and soldiers who fired at demonstrators with Kalashnikov rifles, disobeying orders.

The October coup derailed a power-sharing agreement between the army and civilians negotiated following the 2019 ouster of longtime autocrat Omar al-Bashir.

Regular protests have continued across the country, rejecting the ruling military authority and calling for justice for the more than 250 people killed since Bashir was ousted.

They have also called for the release of detained activists, who according to Dieng "have never met their lawyers".