AMSTERDAM (Reuters) - Dutch police said Sunday they had arrested a 27-year-old man on suspicion of sexually abusing up to 50 children at childcare centers in Amsterdam, and for the distribution of child pornography.

The man, who was arrested on December 7, worked as a substitute carer at daycares in the Dutch capital from February 2007, but also advertised for work as a babysitter over the Internet.

At a late-night press conference, Amsterdam police chief Bernard Welten said the man is suspected of abusing between 30 and 50 children, but stressed investigations were ongoing.

Referring to a “large and complex” case, Amsterdam chief public prosecutor Herman Bolhaar said the man is suspected of abusing children aged up to the age of four and published a photo of the suspect to warn parents of possible victims.

“At this moment we do not precisely know how many children are the victims of this 27-year-old man,” Bolhaar said.

The investigation was launched after child pornography believed to have originated from the Netherlands was found in the United States. The man was arrested after a victim of sex abuse was identified in a Dutch television crime show.

The man’s 37-year-old male partner has also been arrested on suspicion of possession of child pornography. He is not suspected of sexual abuse and will appear in court Monday.

Dozens of parents were informed about the case in two meetings at an Amsterdam hotel Sunday night.

The case comes just months after 60-year-old swimming teacher Benno Larue was sentenced in July to seven years in jail for the sexual abuse of 40 girls over a period of many years. Most of the girls were very young and had learning difficulties.