At least seven people were killed after a South Sudan hospital and market was bombed for fear of a civil war resuming, a medical charity said.

Doctors Without Borders (MSF) said the helicopter gunship threw a bomb at the pharmacy of its hospital run in Old Fangak in Zhonglai State, burned it and fired it for 30 minutes. Doctors Without Borders said a drone subsequently bombed the local market.

Doctors Without Borders said the hospital is the only one in Fagaac County with a population of more than 110,000 people and all its medical supplies were destroyed.

The charity said the attack caused 20 people to be injured, which was a "clear violation of international humanitarian law."

In recent weeks, Nicholas Haysom, who led the UN mission in South Sudan, warned that the country was “on the brink of returning to the full-scale civil war.”

These concerns were caused by a dispute between Salva Kiir and Vice President Riek Machar.

Hours before the bombing, military chief Paul Majok Nang promised a punitive strike after hijacking several barges on the river.

He blamed the attacks on militias linked to Vice President Machar, who has yet to comment on the claim.

Machar was arrested in March with several of his colleagues and was charged with attempting to cause a rebellion.

The government recently listed the counties it considers to be hostile - in other words, related to Machar.

This has increased suspicion of South Sudan and could involve another conflict between the country’s two largest ethnic groups.

South Sudan gained independence from Sudan in 2011, but two years later, when President Kiel rejected Machar as vice president, a civil war broke out, accusing him of planning a coup.

The ensuing conflict was largely racial struggle between supporters of the two leaders, killing about 400,000 people and 2.5 million people were forced to leave their homes - more than one-fifth of the population.

A peace agreement was reached in 2018, with a united government in charge with the same or two, but the elections that should have been called since then have not happened.

The peace agreement also aims to see the end of all militias and the formation of a joint army - but that did not happen, and many armed groups remain loyal to different politicians.

The current crisis was triggered earlier this year, when White militias allied with Machar during the Civil War clashed with troops in the Upper Nile State and occupied military bases in Nasir.

Then, in March, a joint helicopter attempting to evacuate troops caught fire, killing several deaths, including a senior army general.

Rights groups have been calling on the military to stop bombing civilian areas.

Other reports by Yemisi Adegoke and Nichola Mandil