Sudanese security forces shot and killed four protesters on Thursday during demonstrations by tens of thousands who defied a security lockdown and severed communications to rally against military rule, medics said.

For more than two months, pro-democracy activists have kept up a campaign of street demonstrations against a military takeover in October.

A crackdown on the protests has now seen at least 52 people killed, according to the independent Doctors' Committee, which is part of the pro-democracy movement.

A Sudanese protester flashes a victory sign and waves a flag during a demonstrations demanding civilian rule in Khartoum on December 25; more protests are planned for Thursday
A Sudanese protester flashes a victory sign and waves a flag during a demonstrations demanding civilian rule in Khartoum on December 25; more protests are planned for Thursday AFP

On Thursday, security forces killed with live bullets four protesters in Omdurman, twin city of the capital Khartoum, and wounded dozens, they said.

"We call on doctors to come to the Arbain hospital in Omdurman because the putschists are using live rounds against protesters and preventing ambulances from reaching them," they added.

Their plea was posted on social media accounts of Sudanese living abroad as authorities had severed domestic and international phone lines.

Map of the Sudanese capital of Khartoum
Map of the Sudanese capital of Khartoum AFP / Cléa PÉCULIER

Web monitoring group NetBlocks said mobile internet services were also cut.

Communications were restored by evening when the demonstrators had dispersed.

The US embassy, which had called for restraint in the use of force, condemned the killing of protesters and also deplored "the violent attacks by Sudan's security services on media outlets and journalists."

United Nations Special Representative Volker Perthes called for "credible investigations into these violations".

Sudanese demonstrators carry posters of protesters killed during earlier rallies, as they march in Khartoum against the army on December 30
Sudanese demonstrators carry posters of protesters killed during earlier rallies, as they march in Khartoum against the army on December 30 AFP

Despite the risks, protesters chanted "no to military rule" during rallies in several part of Sudan demanding a transition to a civilian government.

Sudanese demonstrators on December 30; at least 48 people have been killed in protest-related violence, according to the independent Doctors' Committee
Sudanese demonstrators on December 30; at least 48 people have been killed in protest-related violence, according to the independent Doctors' Committee AFP

They came within a few hundred metres (yards) of the presidential palace, the headquarters of top General Abdel Fattah al-Burhan who seized power on October 25.

Troops, police and paramilitary units launched multiple tear gas canisters into the crowd.

"The revolution continues," protesters shouted, beating drums and waving flags.

"No to military rule" and "soldiers back to the barracks", they chanted in Khartoum and Omdurman.

A Sudanese demonstrator sits atop a traffic light as thousands protest against the army in the capital Khartoum on December 30
A Sudanese demonstrator sits atop a traffic light as thousands protest against the army in the capital Khartoum on December 30 AFP

Security forces deployed in strength across the capital, using shipping containers to block the Nile bridges that connect the capital with Omdurman and other suburbs.

The authorities also installed new surveillance cameras on major thoroughfares for Thursday's protests.

Witnesses reported similar anti-coup protests in Wad Madani, south of the capital, and the cities of Kassala and Port Sudan in the east.

Saudi television Al-Arabiya said several of its journalists had been wounded in an attack by security forces on its Khartoum office

Another Saudi channel, ASharq, also reported that security personnel prevented its reporters from covering the anti-military rallies.

Burhan, who held civilian leader Prime Minister Abdalla Hamdok effectively under house arrest for weeks, reinstated him on November 21 under a deal promising elections for July 2023.

Protesters said the deal had simply given a cloak of legitimacy to the generals, whom they accuse of trying to reproduce the former regime of autocratic president Omar al-Bashir, toppled in 2019 following mass protests.

"Signing with the military was a mistake from the start," one protester said, accusing the generals of being "Bashir's men".

The Nile bridges were also blocked for previous protests on December 25, when tens of thousands also rallied.

About 235 people were injured during those demonstrations, according to the Doctors' Committee, and tear gas was fired at demonstrators.

Activists have condemned sexual attacks during December 19 protests, in which the UN said at least 13 women and girls were victims of rape or gang-rape.

The European Union and the United States issued a joint statement condemning the use of sexual violence "as a weapon to drive women away from demonstrations and silence their voices".

Sudan still has no functioning government, a prerequisite for the resumption of international aid cut in response to the coup.