The billionaire founder and chairman of Evergrande was placed under arrest Hui Ka Yan, Bloomberg News reported on Wednesday.

Citing people with knowledge of the matter, the agency commented that Hui, who founded Evergrande in 1996 in the southern city of Guangzhou, was taken into police custody earlier this month, and is under confinement “in a designated location.”

It is unclear why Hui is under “home surveillance,” a type of police action that falls short of formal detention or arrest and does not necessarily mean the Evergrande founder will be charged with a crime or offense. However, the measure means he cannot leave the site, meet or communicate with others without approval;, under China’s Criminal Procedure Law. Passports and identity cards are then handed over to the police, but the process should not exceed six months, according to the law.

Evergrande is the world’s most indebted real estate developer, by total liabilities over $300 billion and has been at the center of an unprecedented liquidity crunch in China’s real estate sector, which accounts for about a quarter of its economy. Guangdong police and Evergrande did not respond to requests for comment.