The chairman of China Evergrande Group, the world s most indebted property developer, has been placed under police surveillance, raising further doubts about the company s future. Evergrande has been facing a liquidity crisis and has defaulted on offshore debt payments. The company s financial troubles have led to concerns about contagion in China s banking sector. Evergrande has been trying to restructure its debt, but a group of offshore creditors is planning to petition for the developer s liquidation if it fails to submit a new debt revamp plan.