Four men suspected of sending an internet-congesting 5.4 billion spam emails to promote a dating website have been arrested in Japan.
Yoshimitsu Hirono, 47, president of Tokyo-based dating website Takumi Tsushin, and three other suspects, are charged with distributing 90m junk mail messages a day in July and August last year.
"Spammers may make use of computers in China to make investigations more complicated and to take advantage of lower infrastructure costs."
Competition between dating sites in Japan is fierce, and the suspects are suspected of turning to illegal means in to gain an edge.
According to the Daily Mainichi Takumi Tsushin made 120 million yen ($1m) a month via its partner matching services.