Representatives of Sudan's regular army and the paramilitary Rapid Support Forces remained in the Saudi coastal city of Jeddah despite the earlier collapse of ceasefire talks, the Saudi foreign ministry said.

A five-day extension of a US- and Saudi-brokered but oft-ignored truce formally expired Saturday evening, with no signs of the conflict abating in Sudan and fears that the rival sides were poised for an escalation.

The Saudi and US mediators nonetheless called for "the parties to agree to and effectively implement a new ceasefire, with the aim of building to a permanent cessation of hostilities," Riyadh said.

The last truce was agreed to allow desperately needed humanitarian aid and safe passages into areas of Sudan ravaged by the fighting, but like all that preceded it was routinely violated by both sides.

The Sudanese army on Wednesday withdrew from the talks in Jeddah.

A day later, the US-Saudi mediators declared them officially suspended, with Washington saying it was ready to resume the talks once the parties were "serious" about the ceasefire.

Sunday's statement comes two days before US Secretary of State Antony Blinken is due to arrive in Saudi Arabia, with discussions on Sudan likely to be on the agenda.

The US on Thursday slapped sanctions on the warring parties, holding them both responsible for provoking "appalling" bloodshed.

More than 1,800 people have been killed in over seven weeks of fighting, according to the Armed Conflict Location and Event Data Project.

The United Nations says 1.2 million people have been displaced within Sudan and more than 425,000 have fled abroad.

Some 25 million people, more than half Sudan's population, are now in need of aid and protection in what was already one of the world's poorest countries even before the conflict, according to the UN.

180 buried unidentified

From the battle ground, persistent fighting in Sudan's twin flashpoints of Khartoum and Darfur has forced volunteers to bury 180 bodies recovered from combat zones without identification, the Sudanese Red Crescent said.

Since fighting between Sudan's warring generals erupted on April 15, volunteers have buried 102 unidentified bodies in the capital's Al-Shegilab cemetery and 78 more in cemeteries in Darfur, the Red Crescent said in a statement Friday.

Both regular army chief Abdel Fattah al-Burhan and his deputy-turned-rival, paramilitary commander Mohamed Hamdan Daglo, have issued repeated pledges to protect civilians and secure humanitarian corridors.

But Red Crescent volunteers, supported by the International Committee of the Red Cross, have found it difficult to move through the streets to pick up the dead, "due to security constraints," the Red Crescent said.

Entire districts of the capital no longer have running water, electricity is only available for a few hours a week and three quarters of hospitals in combat zones are not functioning.

The situation is particularly dire in the western region of Darfur, which is home to around a quarter of Sudan's population and has never recovered from a devastating two-decade war that left hundreds of thousands dead and more than two million displaced.

Hundreds of civilians have been killed, villages and markets torched and aid facilities looted, prompting tens of thousands to seek refuge in neighboring Chad.

More than 1,800 people have been killed in the fighting, according to the Armed Conflict Location and Event Data Project.

Medics and aid agencies have said repeatedly that the real death toll is likely to be much higher, because of the number of bodies abandoned in areas that are unreachable.