Tokyo police and customs officials served fresh arrest warrants on three Taiwanese men Monday for allegedly smuggling about 154 kg of stimulant drugs into Japan.

The suspects allegedly hid the drugs inside 216 cardboard boxes containing lighting equipment that was shipped from Guangdong, China, to a dock in Koto Ward, Tokyo.

Tokyo Customs staff found the drugs while inspecting the imported goods and conducted what is known as a "controlled delivery," whereby the drugs were delivered to a warehouse in Kisarazu, Chiba Prefecture, with the knowledge of police.

The suspects were apprehended allegedly red-handed on July 24 when moving 5 kg of the drugs from the warehouse. The drugs were confiscated the same day from the warehouse and from an apartment in Kisarazu where the suspects lived.

The police said the suspects entered Japan in July with tourist visas, and have denied any wrongdoing.

They said they are further investigating a possible distribution network between China and Japan.