Extremely rare audio has emerged online that is believed to be of an interview with the only adult known to have spoken out about an infamous 1966 mass UFO sighting in Melbourne.

On April 6, 1966 over 300 students and some staff reportedly witnessed a UFO flying silently in the sky before disappearing behind some nearby trees.

Andrew Greenwood was a teacher at Westall High School when the object was spotted and is one of the only adults to have spoken about his experience.

It has been 52 years since the alleged sighting but there are very few eyewitness details that have emerged in that time.

Though rare audio, believed to be of an interview between Mr Greenwood and American physicist, Dr James E McDonald, may shed some light on what really happened.

The audio was recently published by the YouTube channel QUFOSR and claims to be a “huge piece of evidence for the case”.

A link to the audio was sent to news.com.au by the owner of the channel, who believes it may be the first time the interview has been posted online.

A recording of Mr McDonald describing the interview has been posted online before but audio of the actual interview is very rare.

Though news.com.au cannot verify the claims it is Mr McDonald and Mr Greenwood speaking on the tape, it is still brings an interesting perspective on the baffling case.

At the beginning of the interview Mr Greenwood told Mr McDonald that he initially brushed off the girl that ran into his classroom claiming there was a UFO outside.

However, at recess time, he thought he might as well go have a look outside, purely out of curiosity, it was then that he saw about 300 students and a few teachers all gathered on the oval.

“I observed the object everyone was looking at. It was grey against a blue grey sky so I didn’t see it immediately,” Mr Greenwood said.

“The only thing I’ve got to compare it against is some smaller sized cessna aircraft and it was approximately two thirds the length of one of those.”

He said it was hard to make out the exact shape but the best way he could describe it was a big plate with a bulge in the middle.

According to Mr Greenwood, the object moved in a very strange way and was a lot faster than any other aircraft he had ever seen.

“It did hover at times, it seemed to be able to accelerate and disappear out of sight and then someone would see it over in another part of the sky,” he said.

“It moved a considerable distance away very rapidly and then moved back again.”

At one point the object moved towards the crowd, but it moved in such a way that it was impossible to know it was moving until it was right in front of them.

“It came towards us, not that we could see it actually coming towards us, but we could see that it was closer now than it was before. It would go up and down. It could move slowly, but generally it seemed to hover or move really fast,” he said.

The sudden appearance of a light plane made the encounter even more bizarre, with Mr Greenwood noting the UFO seemed to be playing some sort of game with the planes.

“[The plane] approached it and then tried to move around it and [the UFO] moved over to another part of the sky very rapidly. The plane followed it over and it moved back again,” he said.

“It seemed to be playing cat and mouse with the plane.”

More planes started to arrive and by the end Mr Greenwood said there were about five planes in the sky with the object.

According to the teacher the UFO was in the sky for about 25 minutes from when it was first noticed and then suddenly it just disappeared.

“It just vanished. It did one of its accelerations and then no one could pick it up again. It was gone,” Mr Greenwood said.

The incident understandably attracted a lot of attention from the local media, with The Dandenong Journal covering the event in great detail and running two front page stories on it.

The Age also ran a small article about the sighting, writing that the unidentified object may have been a weather balloon.

Even though it is the largest mass sighting in Australia to date, hardly any other newspapers made mention of the event, apart from The Sun and The Herald running a few cartoons poking fun at the claim.

At the time, there were a lot of claims that the government was trying to get people to stop talking about the sighting, along with several; witnesses saying sharply dressed men in black suits visited them and warned them from speaking about the incident.

Despite over 300 people seeing the light planes in the sky with the object, the closest airport, Moorabbin, denied having any planes in the sky at that time.

“I drive past (Moorabbin) several times a day and there is never a time when there’s not planes taking off or coming in,” Mr Greenwood can be heard saying.

“So I think it was rather a silly statement for them to make that at that time there were no planes in the sky.”

When Mr Greenwood tried to speak with the physical education teacher who also witnessed the event all she would admit is that she “saw something” but then refused to speak about it anymore.

He also said he was met with complete denial from the headmaster who didn’t want to hear anything about it and even accused him of being hung over and seeing things.

“He is one of these people that runs his school on the book and if it’s not in the book you don’t do it. And there is nothing about how to handle UFO sightings in the book. Therefore you ignore them,” Mr Greenwood said.

He said that after the incident the school received a visit from the Royal Australian Airforce but the headmaster didn’t want to hear anything they had to say and “promptly told them to get lost”.

The interview offers a rare first-hand account of what may have happened that day.

The sighting sparked worldwide interest, with people still debating about what those students and staff actually saw.

Some believe it was definitely an alien encounter while others suspect it may have been new government technology.

@allyjfoster