Wong Kwong-yu - once the mainland's richest man - and his wife have had HK$1.66 billion in assets frozen by a Hong Kong court following an application by the Securities and Futures Commission. Mainland authorities are investigating Mr Wong, formerly chairman and the biggest shareholder of Hong Kong-listed Gome Electrical Appliances Holding, for economic crimes. He was detained in November. His whereabouts remain unknown. Two weeks ago a company called Shinning Crown Holdings - through which Mr Wong holds Gome shares - was used to raise funds to enlarge his stake in the retail giant. The company is among those subject to the court order. The freezing of the couple's assets signals that regulators on both sides of the border are ramping up efforts against Mr Wong, who built Gome into the mainland's largest electrical retail chain. The High Court ordered Mr Wong, his wife Du Juan, Shinning Crown Holdings and Shine Group - the two companies through which Mr Wong holds his Gome stake - not to remove from Hong Kong assets worth up to HK$1.66 billion. The Court of Appeal recently upheld the SFC's powers to freeze assets as part of investigations. Despite his detention, Mr Wong raised HK$400 million two weeks ago selling Gome shares to buy new ones as part of a share offer, and reportedly made a tidy profit. Mr Wong's case is being watched closely in Beijing because of its implications for the mainland's ambitions to improve corporate governance. The case has uncovered a maze of suspected economic crimes and other offences. Mr Wong has not been charged with any crime. 'The impact goes beyond rational financial analysis,' said Randy Zhou, an analyst with UBS Securities. The SFC is also seeking a declaration that the defendants contravened a section of the Securities and Futures Ordinance dealing with fraud and deception. In addition, it is seeking a court order to make the couple pay compensation to Gome. Mr Wong resigned as Gome chairman in January after his detention in Beijing. He has been linked to a widening corruption inquiry that has seen the arrest of senior officials including Zheng Shaodong, a former assistant minister of public security, and Hong Kong businessman Lin Chiu. The Hurun Report ranked Mr Wong the mainland's richest man last year. His major asset is his 4.87 billion shares in Gome, worth HK$12.51 billion based on the stock's closing price yesterday of HK$2.57. His wife holds 205 million shares, worth HK$526 million. The SFC filing said Mr Wong held HK$57.96 million in Bank of China accounts on dates between July 24 and July 29 and HK$50,950 in an HSBC account on July 15. He and his wife had HK$1.57 million and US$17, 957 in joint BOC accounts on dates from July 24 to July 27. The court said the order would remain in force until September, when a further hearing will be held unless the defendants have secured the assets in question or paid HK$1.66 billion into court. The appeal court last month confirmed the SFC's powers to seize assets when the regulator won a legal battle involving two cases of alleged insider dealing in which the defendants had sought to block attempts to freeze their assets or to force them to compensate victims.