NORTH Melbourne forward Nathan Thompson was one AFL player who received a threatening letter earlier in the season.

The Kangaroos released a statement on Friday morning confirming Thompson received the letter, it was forwarded on to the club's chief executive Eugene Arocca, who passed it on to police.

North's statement comes after confirmation Victoria Police are investigating serious threats, including death threats, allegedly made against a number of AFL players

Adelaide also released a statement on Friday confirming a player, who wasn't named, was the subject of a threatening letter the club received earlier in the year

The letter to the Crows was forwarded to club chief executive Steven Trigg in May this year and passed on to police. Investigations into that letter are continuing in South Australia.

The Nine Network reported on Thursday night that five players from five different AFL clubs – three of them Victorian – had received death threats in letters sent to the clubs.

The report, aired on The Footy Show, did not name the players or clubs involved, but North Melbourne has since named Thompson.

Nine became aware of one threat to one player last week, but withheld the report from last week's Footy Show on police advice.

It was not clear whether the threats came from one or a number of sources and Victorian police would confirm only that an investigation into the threats was taking place.

"Moonee Valley criminal investigation unit detectives are investigating a series of threatening letters allegedly sent to a number of AFL players," Victoria Police spokesman Adam West said.

"Victoria Police takes threats made against any person extremely seriously and is currently investigating these matters."