One of the four suspects believed to be behind a string of robberies across Japan is expected to be returned from the Philippines in the next few days, the Southeast Asian country's justice minister said Tuesday.

The other three suspects requested by Tokyo for transfer to Japan will be sent once certain conditions are fulfilled, Philippine Justice Secretary Jesus Crispin Remulla said at a news conference.

The four men, who are currently in detention at an immigration facility in Manila, are believed to have remotely coordinated a series of robberies in Japan that began last year using an encrypted messaging app.