A Norwegian man was sentenced to 16 years in prison on Friday for the sexual abuse, including rape, of several hundred underage boys in what was described as the largest such case in the country's history.

For several years the now 27-year-old posed as a young girl online, mainly calling himself Sandra, and used deception and threats to obtain sexual videos from some 460 boys, many under the age of 16.

However the charges against him, which included sexual abuse and rape, only concerned 270 of the victims.

The man, who was also a football referee, impersonated a young girl and promised sweets, smart phones, naked photos or sexual favours to lure his victims to send him videos -- and in a few cases to meet him -- and then demanded more by threatening to publish the videos.

The man admitted to some of the charges against him when he appeared before the Nedre Romerike District Court in the country's southeast.

The sentence is among the tougher handed out for sexual abuse in the Scandinavian country, in line with the prosecution's claim that it was "the largest case of sexual abuse in Norway".

The man's lawyers simply pleaded for the most lenient sentence possible.

The perpetrator was first arrested in June 2016. But he was subsequently released, allowing him to continue his actions until his second arrest in October that year.

He was also ordered to pay 18.6 million Norwegian kroner ($2.2 million, 1.9 million euros) in compensation to his victims.