Yesterday's theft of $16 million worth of diamonds from the convention centre in Wan Chai came despite heightened security. Police and armed private security agents were highly visible at the Hong Kong International Jewellery Show, which opened a day after the killing of Securicor guard Chan Wai-leung, 42, in Kwai Chung on Monday. Despite their presence, diamonds were stolen from two stalls on the first day of the annual jewellery fair. 'I was scared when I saw this police officer armed with a big shotgun hidden in the corner [at the jewellery fair] . . . He was very nice and offered me a seat, but I was too afraid to sit there. But in general I feel safe, and security is good, ' said New York jewellery importer Israel Lefkowitz, one of the stall holders. The organisers, the government's Trade Development Council (TDC), acknowledged yesterday that security was heavier than in previous years. Police have stationed two vans and set up a command post at the centre's main entrance until the show ends on Friday. Many of the 1,187 exhibitors from more than 30 countries have also hired security. In recent years, gems worth tens of millions of dollars have been stolen from jewellery shows held at the convention centre and run by various organisations. 'There are more exhibitors and the exhibition covers more area than last year, so we need to extend security,' a TDC spokesman said. 'There are hidden cameras, undercover agents from the police and private security firms and cameras and TV monitors placed conspicuously in public areas so people know they are under surveillance.' The TDC spokesman said all exits and passageways have guards on the lookout and police on regular patrol said jewellers were encouraged to put samples in 24-hour security boxes. The number of exhibitors is up 20 per cent on last year's figure. Diamonds worth $23 million were stolen last September and last June, a man was arrested after trying to steal a briefcase containing diamonds worth $62 million from the Hong Kong Jewellery and Watch Fair. Five days later, about 60 diamonds worth $5 million were stolen from the same fair.