Besieging Sudanese paramilitary forces pounded El Fasher on Saturday, witnesses said, killing 22 people in Darfur's last city outside their control, according to a hospital source.
El Fasher has become a key battleground in the 15-month-long war pitting the paramilitary Rapid Support Forces (RSF) against the regular Sudanese army.
The battle for the North Darfur state capital, seen as crucial for humanitarian aid in a region on the brink of famine, has raged for more than two months. El Fasher is the only capital RSF doesn't hold.
Witnesses said El Fasher had come under heavy artillery bombardment by the RSF on Saturday.
"Some houses were destroyed by the shelling," one witness said.
A doctor at the city's Saudi Hospital told AFP on the condition of anonymity that the "bombardment of the livestock market and the Redeyef neighborhood killed 22 people and wounded 17."
A pro-democracy activist group said it had counted 22 bodies and the casualty toll was expected to rise.
There was no immediate comment from the RSF, which has in the past denied shelling civilian targets.
Over 300,000 people have fled their homes in El Fasher due to the fighting which started in April, the United Nations said.
Saturday's attack was the deadliest reported bombardment since the start of the month, when 15 civilians were killed in the shelling of another city market.
Intense fighting for El Fasher erupted on May 10, prompting a siege by the RSF that has trapped hundreds of thousands of civilians.
Last month, the United Nations Security Council passed a resolution demanding an end to the siege.
U.S. mediators are expected to make a new attempt in Switzerland next month to broker an end to the fighting. The talks are due to start on August 14.
Previous negotiations in Jeddah, Saudi Arabia, have failed to put an end to the fighting which has displaced millions, sparked warnings of famine and left swathes of the capital Khartoum in ruins.
