A Russian-backed Syrian government offensive against the country’s last rebel enclave has caused one of the biggest waves of displacement in the nine-year-old war.

Islamic State extremists are mounting increasingly bold attacks in Syria and Iraq following their loss of territory in both countries and are planning for the breakout of their fighters in detention facilities, U.N. experts said in a new report.

The UN negotiator leading talks in Geneva to secure an end to fighting in Libya said on Tuesday that high-ranking officials from both sides of the conflict have agreed on the need for a “permanent and lasting” ceasefire to replace an uncertain truce.