Police in Chengdu have cracked what they describe as the mainland's biggest invoice counterfeiting case. Six suspects were arrested and would be charged soon, the People's Daily reported yesterday. The report said police seized fake invoices which, if used to claim tax rebates or other concessions from the government, could have been worth as much as 10.6 billion yuan. The mainland follows the value-added tax system for most transactions. With fake invoices, businesses can claim export rebates from the government and also cheat on taxes. According to the newspaper, police in Chengdu became aware of a gang active near the city's train station as early as June. Intelligence collected showed that the gang was selling fake invoices for profits. Police later detained a suspect identified as 45-year-old Zhang Chengxue and through him were able to locate another suspect, Yang Shugen , who was investigated but released two years ago for a similar offence. After interrogating the two men, police found a basic printing workshop in Chengdu and another underground printing plant on the city's outskirts. Police arrested four more suspects, including one in Jilin province . The newspaper said fake invoices were a high-profit business on the mainland because they were cheap to produce and the counterfeiters could often sell them at 10 times the cost. It quoted police as saying the case was also dangerous because the counterfeiters often recruited uneducated peasant women to sell the fake invoices in crowded public venues to escape police crackdowns. 'Very often these women hold their babies in their hands as protection so that police have second thoughts about arresting them,' the newspaper said.