POLICE believe more high-quality fake US$100 notes will surface throughout the region as part of a multi-million-dollar scam linked to North Korean agents in Macau. This comes as a Chinese bank disclosed it had identified more than US$300,000 (HK$2.3 million) worth of counterfeit US$100 notes in the Portuguese enclave since the first fake bills were noticed by a bank teller here last month. While in Hong Kong, Acting Detective Superintendent Michael Yu Shi-Cheung said another US$1,800 worth of notes had been found at two banks in the territory over the last two weeks. An international investigation into the North Korean scam has been launched by the US secret service. So far, about $6 million in counterfeit US$100 notes have been discovered in at least five financial institutions in Hong Kong and two banks in Macau. Most of the deposits in the enclave are believed to have been made between June 15 and June 20 by a North Korean named Kwak Mun-sang, believed to be in China. He is believed to have taken the fake bills into Macau from the mainland. Mr Yu, the force's top counterfeit expert, expected more notes to surface. ''I think it would be rather naive to say that all the notes have been found,'' he said. ''If a counterfeiter can produce such good notes then why produce such a small amount?'' Most of the notes discovered here have been sent to Washington for chemical analysis, while the Hong Kong police continue to investigate one of the most serious cases of its type in a number of years.