Shelling at a busy market near Sudan's capital has filled a mortuary with bodies, medical charity Doctors Without Borders (MSF) says.

MSF and the Sudanese authorities said the paramilitary Rapid Support Forces (RSF) were responsible for Saturday's attack in the city of Omdurman, which killed and injured more than 100 people - a claim the RSF has denied.

The majority of those killed at the market were women and children, the Sudanese Doctors' Union says.

The RSF and Sudan's army have been locked in a civil war that, over 22 months, has killed tens of thousands and sparked what the UN describes as one of the world's worst humanitarian disasters.

In the past few weeks, the army has stepped up its offensive in Omdurman, which lies across the River Nile from capital city, Khartoum, aiming to regain complete control from the RSF.

Eyewitnesses told the AFP news agency that Saturday's artillery shelling had come from western Omdurman, where the RSF remains in control.

Saturday's explosion caused "utter carnage" at the nearby Al Nao hospital, which was overwhelmed with injured patients, MSF general secretary Chris Lockyear said.

The Sudanese Doctors' Union appealed for nearby medics to assist at the hospital, saying there was an "acute shortage of medical staff".

It added that one shell had fallen "metres away" from the hospital on Saturday.

One survivor of the market attack told the AFP news agency: "The shells hit in the middle of the vegetable market, that's why the victims and the wounded are so many."

Both sides have been accused of targeting civilians, including health workers, and indiscriminate shelling of residential areas.

The recent skirmishes have forced emergency response rooms to shut several health centres, affecting the provision of medical services to thousands of residents.