Reports come from spectators at the Melbourne event who say the drunk man grabbed the swan by the neck, in a “cruel attack”.

Racegoer Leanne Wickendon was leaving the track when she saw a man pick up a bird and swing it two or three times before flinging it into Albert Park lake.

“To witness such disgusting behavioir was very upsetting and for me ruined what was otherwise a great festival weekend,” she posted on the event’s Facebook page. “I hope the girl who took photos of this creep manages to get him punished for such a cruel attack on this beautiful creature.”

Australian Grand Prix boss Andrew Westacott said it was unlikely the act was caught on CCTV, so urged anyone with evidence, or witness accounts, to come forward.

He said the event organisers had received two reports of the swan act – one on its Facebook page and another via a call to the emergency control centre. Police were also alerted at the time, but were “unable to detect any offense”.

The Formula One was won by McLaren Mercedes driver Jenson Button.