The paramilitary Rapid Support Forces (RSF) had since the outbreak of the war with Sudan's army in April 2023 encircled both the Signal Corps in Khartoum North and the General Command of the Armed Forces, its headquarters just south across the Blue Nile river.

"Our forces were able to lift the siege on the Signal Corps," the source in the Sudanese army told AFP.

With a months-long communications blackout in place, AFP was not able to independently verify the situation on the ground.

The RSF could not be immediately reached for comment.

"This victory opens the way to link our forces in Bahri (Khartoum North) with our forces in the General Command," the military source said, requesting anonymity because he was not authorised to speak to the media.

A military source had previously told AFP the army was advancing closer to Khartoum North following days of military operations aimed at dislodging the RSF from fortified positions in the city.

This comes around two weeks after the army reclaimed Al-Jazira state capital Wad Madani, just south of Khartoum, securing a key crossroads between the capital and surrounding states.

The army and the RSF had seemed to be in a stalemate since the military nearly a year ago seized control of Omdurman -- Khartoum's twin city on the west bank of the Nile.

RSF has controlled Khartoum North on the east bank.

They have regularly exchanged artillery fire across the river, with civilians reporting bombs and shrapnel often hitting homes.

The military source said Friday's advance "will secure Omdurman from the artillery shelling launched from Bahri".

Across the northeast African country, the war has claimed tens of thousands of lives and uprooted more than 12 million people in what the United Nations calls the world's largest internal displacement crisis.

Famine has been declared in parts of Sudan but the risk is spreading for millions more people, a UN-backed assessment said last month.

Before leaving office on Monday, the administration of United States president Joe Biden sanctioned Sudanese army chief Abdel Fattah al-Burhan, accusing the army of attacking schools, markets and hospitals and using food deprivation as a weapon of war.

That designation came about one week after Washington sanctioned RSF leader Mohammad Hamdan Daglo and said his forces had "committed genocide."