A military takeover led by army chief Abdel Fattah al-Burhan last year derailed a fragile transition after the 2019 ouster of long-time autocrat Omar al-Bashir.

For 12 months, near-weekly protests have been met with force, and efforts by the United Nations and other international actors to bring Sudan's military government and civilian leaders to the table have stalled.

The crowd that gathered Saturday in front of the headquarters of the UN mission in Sudan chanted pro-Bashir slogans and burned photos of UN envoy Volker Perthes.

One demonstrator told AFP he wanted "the armed forces to side with the people and kick Volker out today".

Some waved banners reading "No to foreign interference" and "No to the UN".

With police standing nearby, an AFP correspondent said some protesters chanted "Volker, you mole, we beheaded Gordon," referring to British general Charles Gordon who was killed in an 1885 revolt in Sudan.

The country has been grappling with deepening political unrest and a spiralling economic crisis since the military takeover, on October 25, 2021.

Civilian leaders have refused to negotiate with the military before it commits to a timetable for full withdrawal from power.

Pro-democracy activists worry that Burhan's regime has reappointed Bashir loyalists to official positions, including in the judiciary that is now trying the former Islamist dictator.

On Thursday, security forces fired tear gas at thousands of demonstrators demanding an end to military rule.

The crackdown on protests has killed at least 119 people, according to pro-democracy medics.