Five men have been arrested after they allegedly attempted to smuggle about 110 kg of narcotics hidden inside construction machinery transported by ship to the port of Hakata in Fukuoka Prefecture, according to authorities.

The five men, aged between their 30s and 50s, are from Japan, the United States, Vietnam, Canada and Serbia, according to customs and narcotics control officials.

The Japanese national, identified as 37-year-old Ryuji Kitamura, and the four others, whose identities were not immediately known, have denied the charges. Kitamura manages a company that exports and imports construction machinery and other products.

Their alleged crime came to light earlier this month after authorities confiscated narcotics from a steam roller transported by ship from the Netherlands to Hakata via Busan, South Korea. The amount found had an estimated street value of about ¥9 billion.

The authorities were tipped off by Australian police about a drug smuggling deal involving an international crime organization. Using an investigative technique called controlled delivery, they replaced the narcotics contained in the vehicle's roller with an innocuous material and allowed the deal to go forward under surveillance. The five were arrested Friday for allegedly possessing the replaced contents from the imported vehicle with intent to receive narcotics.