Sudan’s army has launched a major offensive in Khartoum against its paramilitary opponents in a fierce battle for control of the capital.

Sudanese army forces claimed to have crossed three key bridges over the Nile in an early morning attack to retake neighbourhoods seized by the Rapid Support Forces (RSF).

The assault appeared to be the army’s biggest offensive in Khartoum since it lost control of much of the city at the start of the country’s catastrophic 17-month-long civil war.

The push came ahead of an address by the army commander, Gen Abdel Fattah al-Burhan, at the United Nations general assembly in New York later in the day.

Witnesses reported shelling and air strikes close to the river and columns of smoke rising over the densely populated areas.

“The army is carrying out heavy artillery strikes and air strikes on Halfaya and Shambat,” Ahmed Abdalla, a 48-year-old resident told Reuters.

“The sounds of explosions are very loud.”

The RSF said it had stopped attempts to cross two key bridges into Khartoum and The Telegraph was not able to independently verify the reports.

Sudan’s army and the RSF began a brutal struggle for power in April 2022 when a long smouldering rivalry between Gen al-Burhan and his deputy, Gen Mohamed Hamdan Dagaloa, known as Hemedti, flared into open hostilities.

The RSF, led by Hemedti, has made strong gains in much of the country, which has been turned into a war zone and one of the world’s worst humanitarian crises.

As many as 150,000 people have been killed, while more than 10 million people have fled their homes.

Diplomatic initiatives to halt the bloodshed have repeatedly failed, with envoys saying both sides are acting in bad faith.

The conflict has become further complicated by foreign powers picking sides and pouring arms into the war, in the hope they can gain resources, concessions or influence from the eventual victor.

Earlier this week, Joe Biden, the US president, urged all countries to cut off weapons supplies to the rival generals.

“The world needs to stop arming the generals. Speak with one voice and tell them: ‘Stop tearing your country apart. Stop blocking aid to the Sudanese people. End this war now,” he said.

The United Arab Emirates have been widely accused of arming the RSF, while Russia has played both sides and Iran and Egypt are supporting the Sudanese army.

Antonio Guterres, this week voiced frustration at the role of foreign powers in the “brutal power struggle” in Sudan that has “unleashed horrific violence”.

“A humanitarian catastrophe is unfolding as famine spreads. Yet outside powers continue to interfere, with no unified approach to finding peace,” he said.

RSF forces have taken much of the Darfur region, where they have been accused of ethnically-targeted attacks echoing the region’s 2003 genocide.

The besieged administrative hub of El Fasher is the only city in Darfur still under Sudanese army control. Diplomats and those taking refuge there fear its fall will set off another round of atrocities.