POLICE are investigating a death threat made to a Super League referee.

And that is the most disturbing turn in a tirade of online abuse and ugly scenes in crowds that are becoming more regular in the 13-a-side code.

4 Police are investigating after this threat was sent to referee Robert Hicks

SunSport has learned authorities and the Rugby Football League are looking into the message that is believed to have been sent by a Warrington fan.

Official Rob Hicks forwarded it to the RFL, who in turn alerted the police and a probe is ongoing.

The tweet, sent by someone claiming to be called James Clarke, said: “There ya go have that ya f***ing @therfl scumbags.

“You’ll all be killed tomorrow. Robert Hicks will be shot dead live on TV.

“WATCH AND LEARN. Enough of your corruption. Scumbags.”

4 Hicks was targeted after a recent Challenge Cup game Credit: MAGIPIX

This threat, believed to have been sent after a recent Challenge Cup clash, is the most disturbing part of a developing trend of misbehaviour in rugby league.

SunSport revealed how London Broncos have launched a probe after one of their players was greatly affected after being referred to as ‘disabled’ by an internet troll.

Now a number of stars are thought to have complained of receiving the abuse.

Things are little better on the terraces as St Helens fans claim their coaches had their windows put through by Warrington fans after Thursday’s match.

The Wolves and Catalans Dragons are currently at the centre of an investigation into ugly scenes at the end of their match earlier this month.

4 More and more players and officials are being targeted for abuse Credit: MAGIPIX

Warrington supporters were also involved in ugly clashes with Wigan fans outside the Halliwell Jones Stadium in March.

It is not only them, though, a Salford fan was heard branding one of his own black players a ‘monkey’ during a match at London.

In the Championship, Toronto Wolfpack owner David Argyle fired himself after asking Swinton’s Jose Kenga, ‘Do they allow black people in Swinton?’

At the recent Challenge Cup semi-finals, an Asian TV reporter claimed he had been subjected to racist abuse, with a Hull FC fan allegedly telling him to, ‘F*** off back home,’ and a Halifax supporter asking if he was from Bollywood.

Hull FC fans condemned their own for throwing bottles during the last four defeat to Warrington. Hull KR described supporters fighting among themselves at April’s derby against Hull FC as ‘unacceptable.’

4 Australian Rugby League referee Matt Cecchin received death threats following Tonga's defeat against England Credit: Getty Images - Getty

Rugby league prides itself as being a ‘family game’ as a message relayed over PA systems tells fans – but whenever that is played it is often sarcastically cheered.

And referees boss Steve Ganson has had enough, especially of players contesting calls, saying: “We’ve seen a worrying trend emerging, where certain players seem to feel it is their right to question, to argue or in extreme cases to engage in a running battle with match officials.

“It’s important for me to say publicly now, so that supporters are aware as well as players and coaches – dissent towards the match officials will not be tolerated. It’s up to the players – if they choose to do it, they should expect the consequences.

“I’ve seen examples of players trying to convince referees visually and verbally to rule against the opposition – for me, that’s not acceptable in rugby league.”