South Sudan is reeling from an escalating conflict between the government-aligned army and opposition forces and allied groups that observers say risks returning the country to a full-blown civil war.

Violent confrontations in the world’s youngest country between the military, which is loyal to President Salva Kiir, and insurgents believed to be allied to the suspended vice-president, Riek Machar, have increased in recent weeks.

On Sunday, at least 169 people were killed after armed youth from Mayom county in the north raided a village in neighbouring Abiemnom county near the Sudan border.

The victims included including women, children and members of government security forces, said James Monyluak Majok, the information minister for the administrative area of Ruweng, where Abiemnom is located.

The UN mission in South Sudan said it was sheltering more than 1,000 civilians in its base in the area and providing medical care to those injured. It said about 23 people were wounded in the attack.

Stephano Wieu de Mialek, the chief administrator of Ruweng, said the assault was carried out by people linked to the White Army, a militia that was allied to Machar during the civil war, alongside forces affiliated with Machar’s political party and rebel group, the Sudan People’s Liberation Movement-in-Opposition (SPLM-IO).

The group denied responsibility for the attack and said it had no military presence in the area.

On Monday, Doctors Without Borders (MSF) said 26 of its staff were unaccounted for after recent violence in parts of Jonglei state, which has witnessed intense fighting between government and opposition forces since December.

The humanitarian organisation said on 3 February that its hospital in Lankien had been hit in an airstrike by government forces and later burned and looted, and its health facility in Pieri was looted.

It said of the missing staff: “We have lost contact with them amid ongoing insecurity.”

MSF said it had been forced to suspend medical activities in Lankien and Pieri due to the insecurity.

Machar and Kiir were both members of the Sudanese People’s Liberation Army guerrilla movement that fought for independence from Sudan, which it gained in 2011, with Kiir becoming president and Machar first vice-president.

South Sudan descended into a bloody civil war in 2013 after Kiir fired Machar and later accused him of planning a coup.

Machar founded SPLM-IO and both groups engaged in fighting that killed more than 400,000 people and displaced nearly half the country’s population.

The fighting took place largely along ethnic lines between Kiir’s majority Dinka community and Machar’s Nuer, the second-largest ethnic group in the country.

In 2018, Kiir and Machar signed a peace deal — ending the civil war, creating a unity government of the two parties and returning Machar to the vice-presidency. But implementation of the agreement has barely got off the ground, as the two parties constantly collide over power-sharing.

Last September, Machar was charged with murder, treason and other serious crimes in connection with a deadly attack by the White Army on a government army garrison in Nasir county in the country’s north-east. Kiir then suspended him from his post.

Machar is under house arrest as his trial continues. His supporters say the charges against him are politically motivated, and observers have said that Machar’s prosecution could jeopardise the peace agreement.

Machar’s prosecution and removal from office have inflamed tensions and coincided with the dramatic increase in violence, particularly in the opposition stronghold of Jonglei state where opposition forces captured government outposts in December and the government has been conducting a counteroffensive since January.

Fighting between government and opposition forces there has displaced an estimated 280,000 people over the past two months.

Daniel Akech, a senior analyst for South Sudan at the International Crisis Group, said the government’s “targeting” of Machar has unified the opposition. Akech said that not only did the latest fighting involve rebel groups that were loyal to him but it had also roped in groups that split from him in the past because they now saw him as a “symbolic unifying figure”.

“Even if he’s detained or is incommunicado or cannot issue orders, he has become very effective,” Akech said.

Last Friday, the UN’s high commissioner for human rights called for urgent action to preserve the peace agreement and prevent a return to all-out civil war.

“We are at a dangerous point, when rising violence is combined with deepening uncertainty over South Sudan’s political trajectory, as the peace agreement comes under severe strain,” Volker Türk told the UN Human Rights Council.

Additional reporting by the Associated Press