Congo has severed all diplomatic ties with Rwanda and South Africa said on Saturday that nine of its peacekeepers had been killed amid a surge in fighting with Rwanda-backed rebels in mineral-rich eastern Congo.

Fighting has escalated sharply in recent weeks in eastern Congo, where rebels have seized key towns and are closing in on the city of Goma, the government’s last stronghold in the North Kivu province,

The insecurity has deepened a dire humanitarian situation with 400,000 more people forced to flee their homes this year, according to the United Nations refugee agency.