Witnesses reported seeing battles raging in Sudan's war-torn capital of Khartoum on Tuesday, and residents of a Nile island claimed to be "under siege" due to severe shortages.

Abdel Fattah Al-Burhan, Sudan's army leader, and his former deputy Rapid Support Forces (RSF) commander Mohamed Hamdan Daglo had been engaged in combat for eight weeks.

Witnesses once more described "the sound of heavy artillery fire" in northern Khartoum, despite numerous violated ceasefires providing a brief calm.

There were "clashes with various types of weapons" in south Khartoum, where "the sound of explosions shook our walls," according to witnesses.

The island of Tuti is "under total siege" by RSF forces in the city's center, at the meeting of the White Nile and the Blue Nile rivers, according to resident Mohammed Youssef, who spoke to AFP.

The lone bridge leading to the island has been closed up by paramilitaries, preventing inhabitants from traveling by boat to other areas of the city.

"We can't move anyone who's sick to hospitals off the island," Youssef said, adding that if this continues, "stores will run out of food."

According to the Armed Conflict Location and Event Data Project, more than 1,800 people have died since the violence started on April 15.

The situation is dire in the western region of Darfur, which is home to almost a quarter of Sudan’s people and has never fully recovered from a horrific two-decade war that left hundreds of thousands dead and more than two million displaced.

"We face a massive humanitarian crisis that is only going to get worse with the collapse of the economy and the health care system," the International Federation of Red Cross and Red Crescent Societies (IFRC) warned today.

With "the flood season fast approaching and the looming hunger crisis and disease outbreaks that now are becoming more inevitable," the danger will increase.

The annual rainy season in Sudan starts in June, and doctors have frequently warned that it might render some areas of the nation inaccessible, increasing the danger of waterborne illnesses like malaria and cholera.

According to the UN, around 25 million people, or more than half the population, are currently in need of assistance and safety.

More than 425,000 individuals have escaped to other nations; more than 100,000 have gone to Chad in the west and 170,000 to Egypt in the north.

According to the IFRC, there's an "urgent need for a massive injection of funds" to aid individuals escaping the violence.

As the conflict shows no signs of stopping, the UN has also made a financial appeal.

Last week, after a truce negotiated by the US and Saudi Arabia crumbled and the army abandoned ceasefire negotiations, Washington imposed sanctions on the two warring generals, attributing blame for the "appalling bloodshed" to both sides.