Police have rounded up more than 90 people suspected of participating in a widespread meter-tampering scheme - thought to have cost gas and power providers HK$30 million - to help restaurants lower their utility bills. Authorities launched an operation eight days ago after receiving a tip-off about the practice, which involves more than 100 cafes, canteens, hot-pot shops and restaurants spread across Hong Kong Island, Kowloon and the New Territories, police said. In all, 93 were arrested in "Operation Toughminer" - 80 men and 13 women, aged 25 to 69. Those arrested include the owners of the establishments and other people believed to have tampered with meters. Five of the suspects have been charged with conspiracy to defraud. The others were released pending further investigations. Police said the owners and managers of the businesses gave at least some of the money they saved to other, unnamed individuals involved in the scheme. As evidence, police seized 62 gas meters, 29 power meters, a cache of tools and two private cars. Authorities have warned members of the public not to tamper with the meters that public utilities rely on to fairly administer charges. The police said that, under the Theft Ordinance, business owners who approve or allow people to tamper with their utility meters could be charged with fraud and face sentences of up to 14 years in prison. The police said the operation was conducted in co-operation with the public utilities and that authorities would continue to work with the utility companies to combat crime.