Andrew Westacott promises 'thorough investigation' after fans break ...

Australian Grand Prix Corporation (AGCP) boss Andrew Westacott says there will be a "thorough investigation" after fans managed to break through security and access the Albert Park track, before the race was officially over.

Key points:Red flags caused chaos at the end of the Australian Grand Prix, with only 12 cars finishingIn the chaos, several fans broke through security barriers to gain access to the trackOrganisers said they will go through security footage to understand how the breach occurred

Footage has emerged showing Formula 1 fans at Sunday's grand prix in Melbourne climbing safety fences and squeezing through barriers, just metres away from the speeding cars.

The footage led to an AGCP representative being summoned by stewards on Sunday night to explain the security breakdown, with the FIA and FIA World Motorsports Council investigating what happened.

"A large group of spectators managed to break the security lines and accessed the track while the race was still ongoing," the stewards' report read.

"The security measures and the protocols which were expected to be in place for the event were not enforced resulting in an unsafe environment for spectators, drivers and race officials.

"Furthermore, spectators were also able to reach car No.27 (Nico Hulkenberg), which was parked at exit of turn 2 and which still had its light flashing red (i.e. the car was in an unsafe condition with possible electrical discharge).

"All of this presented significant danger to the spectators; race officials and the drivers."

Westacott told ABC Melbourne that organisers were as yet unaware how the incident unfolded, and they would be carrying out an investigation to figure out what had happened.

"There's a controlled allowance of people to come onto the track after the race has concluded and after the safety car passes," he said.

"Spectators had broken one of the lines, we don't know how that's occurred just yet."

Westacott said officials would trawl security cameras in an attempt to understand how the breach had occurred.

"We met with the FIA last night until late into the evening and ... we are going to conduct a very thorough investigation because there's a protocol that allows this to happen, but it has to happen in a safe manner and there has been a breakdown somewhere," he said.

"We've got a lot of CCTV and we've got a huge amount of footage we're going to have to pour through over the next couple of weeks.

"Motorsport is dangerous ... it could have been horrific. 

"Nobody does anything malicious at motorsport, it's an unbelievably well-behaved crowd but they, I think, had a degree of confusion. We don't know how they got into the area without the right level of authority."

The stewards on Sunday night deemed that the AGCP was in breach of Article 12.2.1.h of the 2023 FIA International Sporting Code — failure to take reasonable measures, thus resulting in an unsafe action and concluded that the AGCP should "urgently present a formal remediation plan to the FIA that adequately addresses the serious concerns above".

Red Bull's Max Verstappen won the race, which was impacted by several red flags that saw just 12 cars cross the finish line.

Spectator hit by debris

William Sweet was sitting with his partner on a mound of grass at turn 2 when he was struck by debris during lap 54 after Kevin Magnussen hit the wall.

He sustained a cut on his right forearm that required treatment from the paramedics attending the race.

"I'm listening to the commentary with a radio pressed up against my ear when [Magnussen] comes around the corner and I watch and there's just like a puff of smoke right at the barriers in front of us," Sweet told ABC Sport.

"He kind of carries on, so I'm following his car … and there's people buzzing around me because they'd seen something flying and then all of a sudden something just hits my arm.

"I didn't think it was that bad at the time and then someone held up a bit of a wheel and I thought, 'That's weird, I think that just hit me'.

"And then blood just dripped on my fiancée's picnic rug. It wasn't bleeding that badly. Suddenly people realised that I'd been hit by the debris."

William Sweet was hit by debris late in the race.(Supplied)

Sweet said he quickly became the focus of attention among the crowd.

"Everyone was really amused by it and wanted a picture with me for some reason. It was just a bit weird," he said.

"I certainly noticed it but I can't say it hurt necessarily. I was just a bit surprised. It looked worse than it was really.

"There was a lot of crashes on that corner and none of the other ones got any debris issue at all. So, it could be a freak accident.

"The piece that hit me would never of been able to go through the barrier. So it must have gone up and over.

"We watched the replays a bunch of times. It hit a wall that goes straight up and kicks inwards, so I don't know how it's done this weird arc. It's almost impossible."