The civil war started in 2013, two years after the country gained independence from Sudan, and almost a third of its 12 million population fled their homes.

Alain Noudehou, UN humanitarian coordinator for South Sudan, said at a news conference: “We are calling for $1.72bn to continue providing life-saving assistance and protection for 6 million people most in need in South Sudan.”

At the same news conference, the country’s humanitarian affairs minister Hussein Mar Nyuot said: “I believe if we don’t get the amount [$1.72bn] and the donors don’t respond to this more crisis in South Sudan will happen.

“This means 2018 might be worse than 2017.”

The UK announced on Thursday a £52m ($69.90m) humanitarian package to help communities in South Sudan, including food, shelter and support.

The conflict started with a row between the president Salva Kiir and his former deputy Riek Machar, who is now in South Africa, and led to a fight along ethnic lines.

Noudehou said humanitarian assistance was needed for people suffering from food insecurity, malnutrition, violence and economic decline. 

The conflict has also led to lower oil production, which was a key income for the country.