Thousands of Sudanese demonstrators joined new protests Thursday against the army's October 25 coup, braving tear gas, the cutting of communication links and a tight lockdown in the capital, AFP correspondents reported.

Demonstrators reached within a few hundred metres (yards) of the presidential palace in Khartoum, headquarters of military chief General Abdel Fattah al-Burhan, before troops, police and paramilitary units launched multiple tear gas canisters into the crowd.

The activists are calling for a transition to civilian rule. Witnesses reported similar anti-coup protests in Madani, south of the capital, and the cities of Kassala and Port Sudan in the east.

Pro-democracy activists have kept up a campaign of street demonstrations against the army's takeover, despite a crackdown that has seen at least 48 people die in protest-related violence, according to the independent Doctors' Committee.

The security forces had deployed in strength across Khartoum in anticipation of Thursday's demonstration.

Army and police patrols criss-crossed the streets, while shipping containers blocked the Nile bridges that connect the capital with its northern suburbs and its twin city Omdurman.

The bridges were blocked off for the last protests on December 26, when tens of thousands took to the streets.

But for Thursday's protests, new surveillance cameras had been installed on the major thoroughfares along which demonstrators were due to march.

For the first time, authorities also cut all phone lines, both international and domestic.

Web monitoring group NetBlocks reported mobile internet services were cut from mid-morning Thursday. Activists use the internet for organising demonstrations and broadcasting live footage of the rallies.

- US appeal for calm -

The US embassy appealed for restraint from the government led by Burhan, which had been counting on a controversial November partnership deal with civilian Prime Minister Abdalla Hamdok to calm public anger.

"The US embassy reiterates its support for peaceful expression of democratic aspiration, and the need to respect and protect individuals exercising free speech," a statement said.

"We call for extreme discretion in use of force and urge authorities to refrain from employing arbitrary detention."

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".

Hamdok had been held under effective house arrest for weeks before being reinstated under the November deal, which promised elections for July 2023.

But the deal was widely criticised as a gift to the military that gave a cloak of legitimacy to its coup.

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

Over 14 million people, a third of Sudan's population, will need humanitarian aid next year, according to the UN Office for the Coordination of Humanitarian Affairs, the highest level for a decade.