The international community’s chief representative in Bosnia has warned that the country is in imminent danger of breaking apart, and there is a “very real” prospect of a return to conflict.

In a report to the UN seen by the Guardian, Christian Schmidt, the high representative for Bosnia and Herzegovina, said that if Serb separatists carry out their threat to recreate their own army, splitting the national armed forces in two, more international peacekeepers would have to be sent back in to stop the slide towards a new war.

International peacekeeping duties in Bosnia are currently the task of a residual EU force (Eufor) that is 700 strong. Nato retains a formal toehold with a headquarters in Sarajevo. The year-long mandate for both is up for renewal this week at the UN security council, but Russia has threatened to block a resolution unless all references to the high representative are removed, potentially undermining Schmidt’s authority as the overseer of the 1995 Dayton peace deal.