The increasingly tribal nature of the conflict in South Sudan is producing strains within the army, says a UN report published on Tuesday.

“Senior and high-ranking SPLA [Sudan People’s Liberation Army] officers have noted to the UN Panel of Experts that there is discontent within the SPLA at the increasing tribalisation of the army,” the 20-page report states.

The panel’s sources attribute these tensions to the army’s reliance on troops from the home area of SPLA Chief of Staff Paul Malong, a Dinka from Bahr el Ghazal in the west of the country. The war has itself “evolved into a violent contest between elements of the Dinka tribe and many of the country’s other tribes,” the experts observed.

A collapsed economy, reflected in a runaway inflation rate and the government’s failure to pay salaries regularly, is heightening tensions within the broader population as well as in the SPLA, the UN panel said.

“After 33 months of war, the South Sudanese economy has effectively collapsed as a direct result of government policies.”

Government spending on services has simultaneously “evaporated,” while an enormous share of revenues is being devoted to the war, including weapons procurement, the five-member panel said.

The South Sudan military recently acquired a pair of jet fighters, the report noted. One of the L-39 jets was seen at Malakal airport on August 16, and it reportedly conducted combat operations against rebel forces the same day.

“The panel has received preliminary reports from two sources that the jets were serviced and painted in Uganda,” the report stated.

It added, however, that the UN experts have not confirmed the origin of the two planes nor determined whether they were purchased or are on loan. Two truckloads of ammunition were also transferred from Uganda to Juba mid-June, according to what the report describes as a high-ranking SPLA source as well as a representative of a country belonging to East Africa’s Intergovernmental Authority on Development.

The report indirectly endorses some advocates’ call for an arms embargo against South Sudan. The continued influx of weapons “contributes to the spread of instability and the continuation of the conflict,” the report states.

In its examination of the tribal animosities fuelling the war, the UN panel singled out a “a self-appointed body of Dinka politicians calling itself the Jieng (Dinka) Council of Elders.”

This grouping has mobilised opposition to last year’s peace agreement, the report says.