Shelling rocked greater Khartoum on Friday as fighting between Sudan's warring generals intensified, despite US sanctions imposed after the collapse of a US- and Saudi-brokered truce.
Witnesses reported "artillery fire" in eastern Khartoum and around the state television building in the capital's sister city Omdurman, just across the Nile.
For nearly seven weeks, fighting between the regular army and the paramilitary Rapid Support Forces (RSF) has gripped Khartoum and the western region of Darfur, despite repeated efforts to broker a humanitarian ceasefire.
The army announced it had brought in reinforcements from other parts of Sudan to participate in "operations in the Khartoum area".
Sudan analyst Kholood Khair said the army was "expected to launch a massive offensive" to clear the paramilitaries from the city's streets.Washington slapped sanctions on the warring parties Thursday, holding them both responsible for provoking "appalling" bloodshed.
The US Treasury placed two major arms companies of the Sudanese Armed Forces, Defence Industries System and Sudan Master Technology, on its blacklist.
It also placed sanctions on gold mining firm Al Junaid Multi Activities Co and arms trader Tradive General Trading, two companies controlled by RSF commander Mohamed Hamdan Daglo and his family.
The State Department meanwhile imposed visa restrictions on both army and RSF officials, saying they were complicit in "undermining Sudan's democratic transition". It did not name them.
Washington announced on Friday that Secretary of State Antony Blinken will next week travel to Saudi Arabia where he will discuss "strategic cooperation on regional and global issues". His trip follows efforts by both countries to broker a durable ceasefire in Sudan.
Analysts question the efficacy of sanctions on Sudan's rival generals, both of whom amassed considerable wealth during the rule of longtime dictator Omar al-Bashir, whose government was subjected to decades of international sanctions before his overthrow in 2019.
So far neither side has gained a decisive advantage. The regular army, led by Abdel Fattah al-Burhan, has air power and heavy weaponry, but analysts say the paramilitaries are more mobile and better suited to urban warfare.
After the army announced it was quitting the ceasefire talks on Wednesday, troops attacked key RSF bases in Khartoum.
One army bombardment hit a Khartoum market, killing 18 civilians and wounding 106, a committee of human rights lawyers said.
The army will want to make "some military gains before committing to any future talks in order to improve their bargaining position", said Khair, founder of Khartoum-based think tank Confluence Advisory.
On Friday, the army said it was "surprised" by the US and Saudi decision to "suspend the talks" without responding to an army proposal.
After its own representatives decided to "suspend the negotiations", they had "remained in Jeddah with the hopes that the mediators will take a fair and more effective position that will guarantee commitment" to the ceasefire, an army statement said.
Since fighting erupted on April 15, more than 1,800 people have been killed, according to the Armed Conflict Location and Event Data Project. The UN says 1.2 million people have been displaced within Sudan and more than 425,000 have fled abroad.
Conditions are especially dire in Darfur, where those fleeing the violence told Doctors Without Borders (MSF) of "armed men shooting at people trying to flee, villages being looted and the wounded dying" without access to medical care, the aid group said Friday.
Later Friday, the UN Security Council extended for just six months the global body's political mission in Sudan, after Burhan accused its envoy, Volker Perthes, of stoking conflict.
The mission was previously renewed for one-year durations, its newly shortened time frame underscoring the country's delicate situation.
When the fighting began, Perthes had been focused on finalising a deal to restore Sudan's transition to civilian rule, which was derailed by a 2021 coup by Burhan and Daglo.
Growing differences between them were supposed to be ironed out in UN-backed talks on the day they turned Khartoum into a war zone.
UN Secretary-General Antonio Guterres repeated his "full confidence" in Perthes. Several other Council members also voiced support for the envoy.
"There needs to be regional and continental leadership to resolve this" conflict, the Norwegian Refugee Council's William Carter said.Current council president the United Arab Emirates and its three African members -- Gabon, Ghana and Mozambique -- "have exceptional leverage on whichever direction the Council takes on this issue", he wrote on Twitter.
The 15 council members also resolved to "condemn the attacks against the civilian population", UN personnel and humanitarian actors, as well as the looting of humanitarian supplies.
Some 25 million people -- more than half Sudan's population -- are now in need of aid and protection, according to the UN.
Aid corridors that had been promised as part of the abortive humanitarian truce never materialised, and relief agencies say they have managed to deliver only a fraction of the needs.
Humanitarian agencies have repeatedly warned of the rainy season set to start this month, when the already difficult conditions "will worsen and rivers will flood, complicating movement and supplies", said MSF's emergency coordinator Christophe Garnier.