Singapore, Sep 28 : Evergrande's chairman Hui Ka Yan has been put under police surveillance as the problems for the Chinese property giant mount, the media reported. Evergrande said its shares would remain suspended until further notice, the BBC reported. It marks another low for the heavily indebted property giant which defaulted in 2021, triggering China's current real estate market crisis, the BBC reported. In August, it filed for bankruptcy in the US in a bid to protect its American assets as it worked on a deal. In a statement on Thursday, Evergrande said Hui "has been subject to mandatory measures in accordance with the law due to suspicion of illegal crimes", without giving any further detail. Hui was once Asia's richest person, worth an estimated $36.2 billion in 2019, according to Forbes. But his wealth has plummeted since then, largely as Evergrande's problems have grown, BBC reported. The latest share suspension comes just a month after the firm's previous 17-month suspension was lifted. Evergrande -- once the world's most valuable property developer -- is at the centre of a real estate crisis threatening the world's second largest economy. With more than $300 billion of debt, the firm has been scrambling to raise cash by selling assets and shares to repay suppliers and creditors. Most of Evergrande's debt is owed to people within China, many of whom are ordinary citizens whose homes have not been finished, the BBC reported. /IANS