Air strikes pounded Sudan's capital on Saturday, as violence reached its fourth week only hours before warring sides meet in Saudi Arabia for the first direct negotiations.

The US and Saudi governments confirmed that direct talks between the rival Sudanese Army and Rapid Support Forces would begin in Jeddah on Saturday amid ongoing fighting despite a truce extension.

A joint US-Saudi statement welcomed the "start of pre-negotiation talks" and called for sustained global support to put an end to the fighting.

Fighting between groups supporting the regular army under Sudan's de facto leader Abdel Fattah Al-Burhan and the paramilitary Rapid Support Forces (RSF) under his former deputy Mohammed Hamdan Dagalo has claimed hundreds of lives in just over three weeks.

Sudan's warring sides have announced multiple truces, but none have effectively taken hold.

The US and Saudi Arabia stated in a joint statement that the army and RSF will undertake "pre-negotiation talks" in Jeddah on Saturday.

"Saudi Arabia and the United States urge both parties to take into consideration the interests of the Sudanese nation and its people and actively engage in the talks toward a ceasefire and end to the conflict," they said.

Read more: Hamdok: Civil war in Sudan 'would be a nightmare for the world'

Witnesses reported airplanes bombed several districts of the capital Khartoum on Saturday morning, when telecoms provider MTN said all of its services had been disrupted.

Burhan had given his backing to a seven-day ceasefire declared by South Sudan on Wednesday, but early on Friday, the RSF said they were extending by three days a previous truce brokered under US-Saudi mediation.

Other nations and organizations involved in this weekend's meetings, including Britain, the United Arab Emirates, the Arab League, the African Union, and others, were included in the US-Saudi statement.

The UN refugee agency, UNHCR, has stated that the war will result in an outflow of 860,000 people.

The UN has also warned that the violence might push an additional 2.5 million people into food insecurity within months, implying that 19 million people will require humanitarian assistance to avoid famine.

According to UNICEF, "the situation in Sudan has become fatal for a frighteningly large number of children."

The IGAD is worried about ceasefire violations in Sudan: bloc mediator

East African nations have voiced worry over ceasefire violations in Sudan and urged the country's conflicting factions to communicate, according to the region's top mediator in South Sudan.

The foreign ministry in Juba said late Friday that President Salva Kiir had discussed "his concerns and those of the IGAD leaders" from the East African regional grouping with the fighting generals in Sudan.

Kiir was appointed by IGAD to oversee regional mediation efforts, and South Sudan declared a seven-day truce last week.

The foreign ministry in a statement stated that President Salva "stressed the need for the parties to observe the ceasefire and send their representatives to an agreed venue to commence talks."

According to the International Institute for Strategic Studies, Sudan's army has over 100,000 men, making it one of the largest in Sub-Saharan Africa.

The British-based research notes that the RSF has 40,000 fighters, but other analysts claim the paramilitaries have 100,000.

Experts believe that Burhan's military has the edge of air superiority.

However, the benefits are limited in Khartoum since they "can't just carpet bomb the city because there are civilians... and both sides have their own ground forces there," according to Krieg.