The UN security council has failed to agree terms for extending a peacekeeping mission in Central African Republic just days after a top aid official warned the country is at risk of sliding into full-scale war.

Jan Egeland, secretary general of the Norwegian Refugee Council, who warned the UN peacekeeping mission is overstretched, said wider efforts to end the conflict were also failing.

“The UN effort is not succeeding, the donor effort is not succeeding and the government is in no way steering the country toward good governance,” said Egeland. “Nor are CAR’s neighbours playing the role of being good neighbours stabilising the country.”

On Thursday, the mandate for the UN’s peacekeeping mission, Minusca, was temporarily renewed for a month, following disagreements over whether it should provide support to the country’s national troops.

Aid agencies have warned that Minusca desperately needs additional resources to improve the number and quality of the mission, which has struggled to contain the crisis and faced allegations of sexual exploitation. But Minusca has struggled to persuade countries to contribute troops, while the US wants to reduce cost. Experts believe the number of troops, which currently stands at 12,000, is unlikely to rise further.

“The mission is not even close to fulfilling its mandate of protecting the civilian population,” Egeland added. “Civilians are routinely targeted, killed, abused – the sexual violence is beyond belief”.

Over a 48-hour period beginning on 31 October, 27,000 people were forced to flee after a camp and surrounding homes were burned and looted following clashes in Batangafo, in the north of the country. The site was “virtually next door” to a UN peacekeeper base, said Egeland.

Displaced by violence, hundred of families are living on the PK5 site in Carnot, where houses have been built so that they have a place to call home. Photograph: Hajer Naili/NRC

He added that pledges made at a Brussels conference in 2016 – when 2.06bn (£1.8bn) was promised by donors – had failed to bring about reconciliation and reconstruction in most areas of the country.

“If it [the conflict] continues like right now, full-scale war is much more realistic than any kind of reconciliation and reconstruction outcome we thought of in 2016,” said Egeland.

“This is a place where a hand grenade and loaf of bread are more or less the same price,” he said, adding that the prevalence of diamonds and other precious metals has intensified violence by armed groups. “It is very easy to get guns and grenades for a low price, and unemployed, desperate young men are even cheaper.”

Conflict broke out in CAR in late 2012, when Seleka rebels – most of them Muslims, and many from Chad and Sudan – overthrew François Bozizé. Predominantly Christian fighters, known as the anti-balaka, retaliated. The number of armed groups, often competing for natural resources, has since multiplied.

Funding shortages have forced agencies to adopt a short term approach, said Egeland, focusing resources on the most crisis-hit areas, only to withdraw support as soon as the emergency is perceived to have faded. In Carnot, in the east of the country, the Norwegian Refugee Council was forced to withdraw a school programme that provided education for young people otherwise vulnerable to recruitment by armed groups.

So far this year, the humanitarian response in CAR has received less than half of the $500m dollars needed. An estimated 1.27 million people have been forced to flee their homes as a result of the violence.

Ferran Puig, Oxfam’s country director in Central African Republic, said aid efforts were severely hampered by insecurity. “A lack of humanitarian access to some areas is really preventing us from moving around outside of the areas [that are] under control of Minusca. When you try to do humanitarian response to communities [elsewhere], it’s very difficult.”

This summer, the UN Office for the Coordination of Humanitarian Affairs warned of a rise in attacks on aid workers in the country, which is among the most dangerous for humanitarian workers. A total of 118 incidents were recorded between April and June.

There are fears over increased violence in areas such as Batangafo and Bambari, in the centre of the country. In Batangafo, 10,000 people fled to a local hospital and many others to the bush after violence erupted two weeks ago, forcing medical staff to cut back services. Roughly 5,000 people remain on the grounds, according to Médecins Sans Frontières.

Staff there normally see an average of 1,000 people for malaria cases each week, but this had fallen to 60 last week following the eruption of violence. “In two weeks’ time we are going to have severe cases of malaria because people are not arriving in the hospital, they are living in the bush,” said Helena Cardellach, field coordinator for Batangafo for Médecins Sans Frontières, which supports the hospital.

Medical workers are also concerned about increased cases of diarrhoea, malnutrition and respiratory infections, especially among children under five.

The Norwegian Refugee Council has called for an urgent review of the humanitarian response in 2019, ahead of the country’s 2020 elections, which it is feared may lead to a further escalation of violence.