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.