Government forces and rebels in South Sudan are now fighting for control of oil regions.
There have now been clashes in the town of Malakal in Upper Nile state.
Anglican bishop Hilary Garang said the situation was one of lawlessness.
"There is no government functioning, there is no light, there is no water and people are fleeing, are going away. The town is divided in two," he told the BBC.
"The two sides are taking positions and fighting can erupt any time they choose.
"Today there is heavy shelling. About five shells fell in the middle of the town in part of the market and also on some houses and even close to my residence where I am, near the church," Bishop Garang said.
The fighting began on 15 December after President Salva Kiir accused former vice-president Riek Machar, who was sacked in July, of plotting a coup. Mr Machar denies any involvement.
The BBC reports the fighting has since spread to half of Sudan's 10 states. Oil production, which accounts for 98% of government revenue, is affected.
