Hong Kong and mainland police have smashed a large cross-border illegal football gambling syndicate, seizing betting slips worth more than one billion US dollars, reports said Thursday. Police officers arrested 93 people from Hong Kong and the mainland in a joint operation late Wednesday, broadcaster RTHK said. A large amount of betting slips were seized during the arrests, including seven billion yuan (1.03 billion US) from the mainland, the broadcaster said. Police said the syndicate mainly received online and telephone bets through more than 400 bank accounts, the largest number of accounts involved in a local illegal soccer betting case, according to Cable TV. 'We identified a trend that the bets were mainly placed via the Internet -- same as other countries or regions,' a police spokesman told the broadcaster. The police said details of the operation would be released in a statement late Thursday. Since the global tournament kicked off last month, police in the financial hub have launched a series of raids that hauled in about 350 million Hong Kong dollars (45 million US) in betting records, Cable TV reported. The betting figures are more than a four-fold increase from the 2006 World Cup when police seized gambling slips worth 75 million Hong Kong dollars, according to the broadcaster. Punters in Hong Kong, a football and horse racing-mad former British colony returned to China in 1997, can bet legally on a variety of sports events including the World Cup through the Hong Kong Jockey Club. About 35 billion Hong Kong dollars in legal bets were placed on football matches in 2009, according to Jockey Club figures. Illegal bookmakers are said to offer better odds and easier credit terms -- although failure to repay can lead to violent reprisals, according to police. 