(AFP) - Fighting raged in the Sudanese capital and a city to the south Wednesday, residents said, pushing more people to undertake dangerous journeys to safety across the country's borders.

Those unable to escape grapple with shortages of food and other essentials, surviving only thanks to Sudanese charity networks among friends and neighbours, as talks to secure the safe delivery of aid yield no noticeable progress.

"We were woken by explosions and heavy artillery fire," one resident of Khartoum's sister city of Omdurman told AFP as smoke drifted over the capital.

During the night, two huge blasts were heard across greater Khartoum, residents of multiple districts said, in the fourth week of battles between army chief Abdel Fattah al-Burhan and his former deputy Mohamed Hamdan Daglo who commands the paramilitary Rapid Support Forces (RSF).

More than 750 people have been killed in the fighting which has wounded more than 5,000, according to the Armed Conflict Location and Event Data Project.

In El Obeid, the North Kordofan state capital, about 350 kilometres (190 miles) southwest of Khartoum, residents on Wednesday also reported fighting and explosions.

More than 700,000 people are now internally displaced by battles that began on April 15, and another 150,000 have fled the country, UN agencies said this week.

An average of 1,000 are registered every day by the International Organization for Migration at the dusty, sun-scorched Ethiopian border town of Metema.

- Checkpoints -

Every person interviewed by AFP in Metema spoke of the terror leading up to their departure -- days spent holed up at home in a city gripped by gunfire and bombings, followed by a 550-kilometre journey haunted by fear of armed robbery en route.

Ethiopian waiter Mohamed Ali, who moved to Khartoum seven years ago, said he left everything behind to flee.

"At each checkpoint, (armed men) searched us... and took whatever they found, including our money and any belongings we had," he told AFP.

The United States and Saudi Arabia said the army and RSF would hold "pre-negotiation talks" in the Saudi city of Jeddah from last Saturday, but there has been no announcement of progress there.

Martin Griffiths, the top UN aid official, has left Jeddah after he "proposed a declaration of commitments for the two parties to guarantee the safe passage of humanitarian relief," a UN spokesman in New York said on Tuesday.

Several aid workers have been killed in the fighting and humanitarian facilities ransacked.

Cindy McCain, World Food Programme executive director, said nearly 25 percent of the agency's food has been looted.

But aid continues to flow into Sudan. Two Saudi Arabian aircraft loaded with humanitarian material landed in Port Sudan on Tuesday, an AFP journalist said.

On Wednesday in Abu Dhabi, a military plane prepared another delivery of aid for Port Sudan.

"It's clear that because of the needs on the ground, we're going to proceed with humanitarian operations whether there's a ceasefire or not," Farhan Haq, deputy spokesman for UN Secretary-General Antonio Guterres, told reporters on Tuesday.

"But in order to make sure that safe passage is guaranteed, we want the parties to adhere to a declaration of commitments."

© Agence France-Presse