Incidents of gold being smuggled into Japan are soaring, with authorities struggling to get a grip on the scale of the illegal trade and admitting they have no idea how much gold is being trafficked into the country. Japanese customs detected a mere eight attempts to smuggle gold into Japan in the 12 months to June 2014, according to the Coordination Division of the Finance Ministry in Tokyo. Underlining the new-found appeal of the underground trade, that figure had rocketed to 177 cases in the year to this June. The majority of the cases that led to legal proceedings involved smuggling via Hong Kong and the authorities in Japan say they are looking into the scale of the problem and will attempt to clamp down harder on the illegal trade. A spokeswoman for the ministry admitted, however, officials were unable to estimate how much gold was being successfully smuggled into the country. READ MORE: Japan’s biggest Yakuza leader in danger of tax evasion charges as rival faction gets hold of illicit funds proof "Based on the statements we have taken from people investigated for gold smuggling, we believe there are a number of groups who are regularly conducting this kind of smuggling and primarily involving Hong Kong," a spokewoman for the ministry told the South China Morning Post . "The majority of the suspects who have been arrested for smuggling are Japanese, but the second-largest number are from Hong Kong," said the spokeswoman. Of the Japanese, a number had links to underground "yakuza" groups, she said. Others who were detained in connection with smuggling include Chinese and South Korean nationals. The 177 cases involved nearly 700kg of gold with a value of 3 billion yen (HK$188.62 million), the ministry said, with the smugglers evading 240 million yen in taxes. Smuggling of gold appears to have become popular since the Japanese government raised the consumption tax on goods from 5 per cent to 8 per cent in April of last year, the ministry said. And the illegal imports are unlikely to dry up in the future as the government is pushing ahead with its plan to increase the tax to 10 per cent in 2017. READ MORE: Mystery gold gifts cheer Japan's tsunami-ravaged port Ishinomaki "It is a fact that the consumption tax on gold in Hong Kong is zero, so it is cheap to purchase gold there and to try to bring it to Japan," the ministry spokesperson said. As many as 60 per cent of the cases involved Hong Kong, including an incident in December of last year in which two members of a Japanese underworld group were arrested at Fukuoka International Airport after disembarking from an aircraft from Hong Kong. Hiroaki Ishimaru, 45, and Yuichi Nagano, 30, were charged with attempting to smuggle four blocks of gold, each weighing 1kg, into Japan in their suitcases. The two men, both members of the Yamaguchi-gumi gang, were arguably unfortunate to be caught as they were subject to a random stop in the airport. Questioned by a customs official who became suspicious about their travel plans, the gold was discovered in a search of their belongings. The gold was worth an estimated 18 million yen and the two men admitted they had been trying to avoid taxes.