Reuters, Khartoum: Artillery fire could be heard in parts of Khartoum and warplanes flew overhead yesterday, residents said, raising fears that intense fighting would erupt and shatter Sudanese hopes raised by an internationally-monitored ceasefire.

Some other residents reported relative calm early yesterday, the first full day of a truce that is being tracked by Saudi Arabia and the United States and is meant to allow for the delivery of humanitarian relief.

Activists wrote to the United Nations envoy to Sudan complaining of severe human rights abuses against civilians that they said took place as the fighting raged.

After five weeks of fierce battles between the army and the paramilitary Rapid Support Forces (RSF), the warring factions on Saturday agreed to a seven-day truce that began at 9:45 pm (1945 GMT) on Monday, aimed to allow for the delivery of aid.

The ceasefire deal, reached in talks in Jeddah, has raised hopes of a pause in a war that has driven nearly 1.1 million people from their homes, including more than 250,000 who have fled to neighbouring countries, threatening to destabilise a volatile region.

"Our only hope is that the truce succeeds, so that we can return to our normal life, feel safe, and go back to work again," said Khartoum resident Atef Salah El-Din, 42.

Although fighting has continued through previous ceasefires, this was the first to be formally agreed following negotiations.

The ceasefire deal includes for the first time a monitoring mechanism involving the army and the RSF as well as representatives from Saudi Arabia and the United States, which brokered the agreement after talks in Jeddah.  US Secretary of State Antony Blinken said the monitoring mechanism would be "remote", without giving details.

"If the ceasefire is violated, we'll know, and we will hold violators accountable through our sanctions and other tools at our disposal," he said in a video message.

"The Jeddah talks have had a narrow focus. Ending violence and bringing assistance to the Sudanese people. A permanent resolution of this conflict will require much more," he added.