MANILA - Police said on Friday that they had arrested four people allegedly involved in the kidnapping of a Japanese boy in Balanga city in the northern Philippine province of Bataan.

Bataan provincial police spokesman Dennis Orbita identified the suspects as Jonathan Benicarlo, his father Pedro, his sister Veronica and one Clarita Benicarlo whose relation with the three was not immediately known.

Police filed charges of kidnapping and serious illegal detention against the suspects for the abduction of six-year-old Paul Kajiwara at Cupang village last Tuesday.

Kajiwara was taken along with the daughter of Veronica.

Orbita said the boy's Filipina mother, Amelia Ranin who is married to a Japanese, received a text message initially demanding a ransom of 150,000 pesos ($3,584). The ransom was then reduced to 30,000 pesos ($717).

Ranin reported the abduction of her son to police and an entrapment operation was set up. Jonathan Benicarlo was the first to be arrested after he agreed to meet the boy's mother for the payoff.

The Japanese boy was later rescued and underwent debriefing under the care of his mother.

"Investigators later discovered that Jonathan is the son of Pedro Benicarlo and brother of Veronica. Soon the investigators tied pieces of information linking the Benicarlo family to the kidnapping with the supposed kidnapping of Veronica's daughter to hide their involvement," said Orbita.

The three other suspects were arrested in succeeding follow-up operations.