Warring factions in South Sudan are battling for control of the country’s dwindling oil production in a sign both sides have given up on faltering peace talks and are instead seeking a military and economic stranglehold over the cash-strapped country.Oil companies have evacuated non-essential staff from fields in Upper Nile state following renewed heavy fighting in Malakal, the regional capital, over the past week, reported the Financial Times on Monday.Malakal lies about 150km south of the fields in Upper Nile state that pump the bulk of the country’s crude. Oil production was hit earlier in the crisis when the rebels in late December took control of Unity state, the other oil-rich region.Oil executives worry the forces loyal to Riek Machar, the rebel leader, will move beyond Malakal, trying to encircle the fields to gain leverage. They said however that a direct attack against the fields was unlikely, the newspaper said.An aide to Machar said the fighting was heading towards the oilfields of Adar and Paloich, in Upper Nile state. “There can be no work because of the fighting. That will stop the oil,” the aide said.Colonel Philip Aguer, spokesman for South Sudan’s army, insisted the fields were so far safe in spite of rebel threats to “either divert or close down the oil industry”. His government last week intervened to overturn a local state directive to shut down the fields.But an industry executive familiar with the situation described a more worrying scenario, with oil groups operating the fields in Upper Nile, including China National Petroleum Company and Malaysia’s Petronas, evacuating some staff from Paloich. “They are lifting as many non-essential workers as they can,” the executive said.Industry officials say oil output has fallen to about 150,000 barrels per day, down 40 per cent from before the start of the conflict, which has killed thousands and displaced 900,000 people.