Police officer is sacked for throwing a projectile at NRL referee after a game - and his top cop father is also under investigation over the incident

A police officer has been sacked from the force after throwing a projectile in the direction of leading NRL referee Ashley Klein following a footy game in Sydney.

The man's father - a senior police officer - remains under investigation surrounding the incident.

The probationary constable was dismissed after an investigation into the conduct of two off-duty officers following an incident at the Sydney Roosters versus Melbourne Storm round seven NRL clash at Allianz Stadium in April.

'An officer has been issued an infringement notice following an investigation into an incident involving two off duty police officers on Thursday 18 April, at a football match in Moore Park,' a police spokeswoman told News Corp.

'The probationary constable was dismissed from the NSW Police. 'An internal investigation into the incident continues.'

The father and son  – as well as a third unidentified person – were also banned from attending sporting matches or events at Venues NSW grounds for at least two years.

It includes the likes of Allianz Stadium, the Sydney Cricket Ground, Accor Stadium and CommBank Stadium.

In addition, the NRL issued ban notices that will see the men unable to attend any footy fixtures across Australia.

A Venues NSW spokesman confirmed in May the trio had been banned for 'offensive behaviour.'

On April 18, a projectile was thrown towards the match officials as they walked from the field following Melbourne's 18-12 victory.

Klein and the two touch judges were not struck by any of the objects.

And on April 11 at Newcastle's McDonald Jones Stadium, an object was also launched at game day NRL officials - but narrowly missed the intended targets.