A blockbuster corruption trial involving Hong Kong property tycoons Thomas and Raymond Kwok opened Thursday, with all five defendants pleading innocent to bribery charges. The brothers, who jointly chair development giant Sun Hung Kai Properties, and Hong Kong's former chief secretary Rafael Hui, were arrested in a major swoop by the city's anti-graft watchdog in March 2012. The Kwoks, aged 62 and 60, were accused of bribing Hui, who once held the second-highest position in the southern Chinese territory's government. The two brothers, ranked fourth on the Forbes Hong Kong 2014 rich list, and Hui are among five people charged with eight offences related to payments and unsecured loans amounting to HK$34 million ($4.38 million). Hui, 66, is accused of misconduct in being "favourably disposed to Sun Hung Kai Properties... and Thomas Kwok and Raymond Kwok" while in office in return for payments, according to a Department of Justice indictment. The charges against Hui also relate to rent-free use of luxury apartments and acceptance of unsecured loans, the document said. All the defendants, who have previously proclaimed their innocence, confirmed their pleas of not guilty when the hearing opened Thursday. Judge Andrew Macrae also issued a warning to the media to confine their reporting to the basic facts of the the trial, following criticism from defence counsel on previous coverage of the case. "I cannot stress this too highly... there are leading counsel who are following everything you write. Please remain within the boundaries," Macrae said. The other accused are another Sun Hung Kai director, Thomas Chan, and Francis Kwan, the former non-executive director of New Environmental Energy Holdings, an investment company. Thomas and Raymond Kwok both smiled as they arrived at court, walking past dozens of photographers who flanked the main entrance, while more than 100 reporters waited inside. Hui declined to discuss the case as he waited outside the court room, but told reporters he was "not feeling relaxed". The case has shocked Hong Kong, where Sun Hung Kai is the biggest property developer by market capitalisation and owns some of the city's most iconic real estate including its tallest tower, the 118-floor International Commerce Centre. The Kwoks have estimated family wealth of US$17.5 billion. Hong Kong is seen as relatively graft-free -- it was ranked the joint 15th cleanest country or territory in 2013 by global corruption watchdog Transparency International. But previous cases have fuelled public suspicions over cosy links between authorities and industry leaders, and the role of the Chinese system of personal connections, or "guanxi" which greases the wheels of business. Former Hong Kong chief executive Donald Tsang ended his term in disgrace in June 2012 after admitting to accepting gifts from tycoons in the form of trips on luxury yachts and private jets. And Hong Kong billionaire Joseph Lau was in March found guilty of bribing a former minister in the gambling enclave of Macau in an attempt to purchase a prime development site in the former Portuguese colony. The Kwok trial, which is expected to last 70 days at the city's High Court, will see a cast of prominent British lawyers in action. Clare Montgomery, who represented the Swedish government when it requested the extradition of WikiLeaks founder Julian Assange from Britain, is representing Thomas Kwok, the elder brother. John Kelsey-Fry, who successfully defended British footballer Steven Gerrard during a court case over a bar brawl in 2009, will epresent Raymond. Another London lawyer, Ian Winter, is to represent Thomas Chan.