Japanese police have arrested eight Japanese nationals allegedly involved in phone scams, after their deportation from the Philippines where they had been apprehended.

The eight Japanese are in their 20s and 30s. They were detained by Philippine authorities in February 2020 under suspicion of working without proper visas at a resort hotel in the northern province of Laguna.

Police say they are suspected of making calls to Japan in an attempt to defraud a woman in the southwestern prefecture of Kumamoto.

Investigative sources say the suspects posed as phone company staffers and told their targets that they had unpaid phone bills. The targets were warned that phone service would be cut off unless they paid up.

The sources say smartphones, PCs and fraud manuals had been discovered in the suspects' hotel rooms.

The group is believed to have been involved in phone fraud cases targeting elderly people in several Japanese prefectures, including Kanagawa, neighboring Tokyo and Shizuoka.

Kanagawa Police sent investigators to the Philippines on Monday night. The eight suspects were deported to Japan on Tuesday, and arrested mid-flight after the plane carrying them entered Japanese airspace.

Upon arrival at Narita Airport, they were transferred to a police station in Kanagawa.

Japanese fraud groups based in Southeast Asia have been caught one after another over the past few years.

Japan's National Police Agency says nine groups have been exposed by local authorities in Thailand, the Philippines, Cambodia and Vietnam since 2019. Japanese police have detained a total of 122 members.