Sudanese forces opened fire killing seven protesters on Monday in one of the deadliest recent mass rallies against a military coup, with UN Security Council members urging Khartoum to exercise the "utmost restraint".
The latest violence, which took place in the capital as well as in other major cities, comes ahead of a key visit by US diplomats, as Washington seeks to broker an end to the months-long crisis in the northeast African nation.
UN special representative Volker Perthes condemned the "continued use of live ammunition" to put down the protests, confirming at least seven people killed and "scores injured", while the US embassy in Khartoum criticised "the violent tactics of Sudanese security forces".
Nine UN Security Council members including Britain and France urged all parties to "refrain from the use of violence", stressing the importance of "peaceful assembly and freedom of expression".
The seven deaths on Monday brings to 71 the number of protesters killed since the army's 25 October takeover led by General Abdel Fattah al-Burhan.
The military power grab triggered international condemnation, and derailed a fragile transition to civilian rule following the April 2019 ouster of longtime autocratic president Omar al-Bashir.
Protesters - sometimes numbering in the tens of thousands - have regularly taken to the streets despite the security clampdown and periodic cuts to communications since the coup.
On Monday, anti-coup medics said three protesters were shot dead by "militias of the putschist military council", while later, the independent Central Committee of Sudan Doctors reported four more were killed during a "massacre by the coup authorities."
Medics reported multiple were wounded by "live rounds".
Sudan's mainstream civilian bloc, the Forces for Freedom and Change, called for "civil disobedience" following what they also dubbed a "massacre".
In protests in Khartoum, as well as its North Khartoum suburb and twin city Omdurman across the Nile, security officers deployed in large numbers, firing volleys of tear gas at protesters.
Several people were seen suffering breathing difficulties and others bleeding due to wounds by tear gas canisters, an AFP correspondent said.
Demonstrators used rocks and burning tyres to create roadblocks, demanding the soldiers go back to their barracks, and chanting slogans in favour of civilian rule, witnesses said.
At nightfall, hundreds of protesters remained on the streets in several parts of Khartoum, while pro-democracy activists led online calls to keep up the demonstrations.
Burhan held an emergency meeting with security chiefs on Monday, who blamed the "chaos" on protesters who "deviated from legitimate peaceful demonstration", and vowed to hold to account those involved in "violations" during protests, according to a statement by Sudan's ruling Sovereign Council.
The authorities have repeatedly denied using live ammunition in confronting demonstrators, and insist scores of security personnel have been wounded during protests, including a police general stabbed to death last week.
Earlier this month, Sudan's civilian prime minister Abdalla Hamdok resigned saying the country was now at a "dangerous crossroads threatening its very survival".
The US envoy to the Horn of Africa David Satterfield and Assistant Secretary of State for African Affairs Molly Phee are expected in Sudan in coming days, in a bid to "facilitate a renewed civilian-led transition to democracy", the US State Department said.
Washington's push comes after the United Nations said last week it will launch talks involving key figures to help resolve the crisis.
"Their message will be clear: the United States is committed to freedom, peace, and justice for the Sudanese people," the State Department said.
Proposed talks have been welcomed by the ruling Sovereign Council, which Burhan re-staffed following the coup with himself as chairperson.
Burhan has insisted that the military takeover "was not a coup" but only meant to "rectify" the course of the post-Bashir transition.