JUBA, Sudan: The cost to Sudan and its neighbors of any return to civil war sparked by January's referendum on independence for southern Sudan could total $100 billion, a report said Thursday. The south is widely expected to choose independence in the Jan. 9 vote – allowed for in a 2005 deal to end a conflict that killed two million people – while the north is anxious to hold on to the oil-rich south. As the referendum approaches, both sides have turned up the rhetoric and analysts have warned of a possible return to hostilities. The report by European and African economic experts put the price of a resumption of civil war in Sudan at more than $100 billion, and said the economic fallout would extend well beyond its borders. “The overall cost would be particularly grave for Sudan's neighbors, amounting to 34 percent of their total annual GDP over a 10 year period,” said the report by Frontier Economics.“Both Kenya and Ethiopia could potentially lose over $1 billion per year,” it said. The report said the region would look like a risky place for investment, Sudan's demand for imports would drop and neighbours would see resources stretched by an influx of refugees while channelling addition funds into their militaries. The estimate includes humanitarian and peacekeeping costs of up to $30 billion – to be met by the international community – and the likelihood that Sudan would surrender $50 billion of its GDP through return to war. Tensions are escalating along the disputed border area. Sudan's northern army on Thursday denied mounting any attacks in the south or north of the border and accused southern authorities of harbouring rebels from the nearby strife