TOKYO: Chinese authorities have detained 35 Japanese nationals in the southeastern province of Fujian for alleged fraud, the Japanese Foreign Ministry said on Wednesday, in what was likely one of the worst cases of telephone scams targeting the elderly.

"We were informed that local authorities notified Japanese consulate-general in Guangzhou on July 3 that they had taken 35 Japanese nationals into criminal custody on suspicion of fraud," a foreign ministry official, who asked not to be identified, told Reuters.

The official declined to give further details because of the investigation being conducted by Chinese authorities. The Nikkei business daily said the Japanese nationals were accused of being involved in telephone scams targeting residents in Chiba prefecture, east of Tokyo.

This could constitute the largest Japanese telephone fraud group found so far operating in China, in terms of the number of people detained, the Nikkei said.

Such groups have increasingly been making calls from China in recent years to evade crackdowns by Japanese authorities, the Nikkei said.

Phone-based fraud targeting senior citizens is widespread in Japan. In a typical case, an impostor calls an elderly person pretending to be their child or grandchild, tells them he is desperately in need of cash and asks them to transfer money to a bank account or hand it to a friend or colleague.

The detained Japanese nationals were alleged to have played the role of callers in the fraud, the Nikkei said. It would be up to Chinese authorities to decide whether to hand them over to Japan, it said.

Japanese police officials were not immediately available for comment.