AFL CEO Andrew Demetriou has apologised for laughing on television when told of an incident in which a dwarf performer was allegedly set on fire by a St Kilda player at "Mad Monday" celebrations.

Demetriou appeared to giggle uncontrollably on Channel Seven's Talking Footy when co-host Luke Darcy told him about the alleged incident.

"I was actually giggling in the beginning because I'd been told by the producer during the break before we went onto the next segment and I thought they were having me on," he told 3AW radio on Tuesday.

"I thought it was a joke."

Demetriou said he didn't believe it was genuine until the story, which had been published online, was read to him.

"After I found out that it was true, it's just reprehensible.

"I was flabbergasted, because in the scheme of all the things that we've been (through this season), that would've been one thing I could have never predicted that we would deal with.

"It wasn't meant to be offensive and I apologise to anyone who is offended."

Victoria Police confirmed to AFL.com.au on Tuesday morning that it had received a complaint over the incident.

"South Melbourne Crime Investigation Unit detectives are investigating an incident where a man has claimed that an unknown person set his clothing on fire with a cigarette lighter," a police spokesperson said. 

"The incident happened yesterday at a function in South Melbourne.

"The victim sustained minor injuries as a result of the prank."

AFL football operations manager Mark Evans said the League was in contact with St Kilda over the incident.

"The players have been playing pranks on each other by setting the shoelaces on fire and singing Happy Birthday and they've singed the clothing of a performer," he said.

He indicated the AFL could step in.

"It's with St Kilda at the moment and once they provide us the details we'll then have a look at it from there.

" I think these practices of mad Mondays and bizarre behaviors and all those sorts of things, I think they're well gone.

"It's certainly bizarre, but it's not conceivable that this is the way we should operate at celebrations for (the) end of the season.

Demetriou said he would be contacting injured performer Blake Johnston on Tuesday to see how he was and to apologise for his initial reaction.

"I wasn't directing my laughter at him, I just couldn't believe the situation could occur."

The chief executive said what made the situation more "incredible" was the fact the AFL had visited St Kilda and other clubs talking about the end of season activities and how to mitigate risks involved in such celebrations.

"I don't understand, unless someone can explain, what the purpose of having lighters? I don't get that."

"We spend our whole lives telling children not to play with matches...

"In the multitude of issues we deal with, this is one that I've never come across and I can't actually believe - and I didn't believe that it was real.

"I understand from a briefing I had this morning that there was no damage done, but it doesn't excuse the behaviour - it doesn't excuse my behaviour, it certainly doesn't excuse what has happening on Mad Monday."

St Kilda is investigating the allegation, which occurred at a South Melbourne hotel. 

Channel Nine's Footy Classified reported that the Saints booked two dwarf performers – Johnston and Arthur Penn Serevetas – as entertainment during their end of season drinks. 

A group of players allegedly began attempting to light each other's clothes on fire as a prank, before one – who has not been named – turned his attention to Johnston. 

The performer was quickly helped by other players and was not physically hurt, but left the function in a distressed state.

Contacted by AFL.com.au on Monday night, a St Kilda spokesperson said: "The club is investigating and is unable to add anything further at this time." 

Serevetas told Footy Classified he viewed the St Kilda player's actions as criminal, and had advised his colleague to take action. 

"A player went behind my friend, got one of those gas lighters that you use to light up a stove, and basically lit him up," Serevetas said. 

"Part of his shirt and pants caught on fire, and after that someone put it out, and he got ticked off, and we left – that was the end of our gig. 

"I said to him after the gig that in my opinion he should pursue it. 

"I think he should get compensated, at least for his shirt and pants. 

"I told him to make sure his skin didn't get burnt or anything like that. 

"In my line of work, we do things that cross a certain line or boundary, but this is beyond – it ventures into criminal kind of stuff." 

It was reported that Johnston – who is also a wrestler – has pulled out of an upcoming engagement with Professional Championship Wrestling as a result of the incident. 

"He's a performer who relies on his self-esteem and confidence to be able to perform at events like this," a Professional Championship Wrestling spokesperson told the program. 

"Tonight he's feeling very miserable and spending time with friends. 

"He's very distressed. 

"The players around him immediately helped to put the fire out and definitely weren't happy with what happened. 

"Blake was humiliated and left immediately. 

"He was lit on fire on the lower back from behind and had no idea of it until feeling it."