A Dutch court has sentenced a former a creche worker who sexually assaulted 67 children and produced child pornography to 18 years in prison.

Identified as Robert M due to the Netherlands' privacy laws, the man abused dozens of extremely young children in two Amsterdam nurseries and at homes where he was babysitting, court documents show.

He then shared videos and images of the acts on the internet.

The 28-year-old Latvian-born Dutch defendant had been dubbed The Monster of Riga by the national press.

Describing the actions of M as "shocking" on Monday, Judge Frans Bauduin said: "Society must be protected."

M, who had admitted to the offences, threw the contents of a glass of water at the judge after being told there were no attenuating circumstances.

His partner, a 39-year-old Dutchman, was sentenced to six years for possession of child pornography and facilitating the commission of the crimes.

Bauduin stressed as aggravating circumstances in M's case a previous conviction for possessing child pornography, the length of time over which the offences were committed, and the age of the victims, some of whom "were not yet talking" when he assaulted them.

Arrested in December 2010, he was employed in nurseries in Amsterdam which looked after children aged from a few months to four years between 2007 and 2010.

From 2009 he also acted as a baby-sitter for parents he contacted via the internet.