The family of missing Australian backpacker Rye Hunt have said they're "understandably cautious" over reports Mr Hunt has been found alive.

Brazilian police believe they have found the Tasmanian "alive and well" on an island in Rio after he disappeared without a trace from a Rio de Janeiro airport.

Overnight reports said Mr Hunt had taken a number of "local drugs" before his disappearance and had a "psychotic episode" which led him to the island where he was discovered.

Brazilian police allege that instead of swallowing the drug in diluted water, Mr Hunt sniffed MDMA in powder format.

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Police are "trying to verify that the man they have is in Rye Hunt", but are yet to make any official confirmations.

Mr Hunt's sister, Romany Brodribb, told news.com.au this morning the family "had not been told anything" by authorities and were anxiously awaiting news.

"We have no confirmation, we're so reluctant," Ms Brodribb said.

"We are understandably cautious about taking this information as fact. We're really, really hopeful but I'm curious to know what their source is.

"We've also not heard from Brazilian police so there's a part of me that's a tiny bit sceptical.

"Obviously this is really heart-wrenching for all of us. That's all I can say."

Mr Hunt had planned a six-month world trip with travelling companion and mate Mitch Sheppard, starting in Thailand for two weeks, South and Central America for two months - including seven days in Cancun followed by a bus trip to Acapulco - before moving on to a two-month trip around Europe, finishing off in Munich, Germany, for Oktoberfest.

MDMA CAUSED 'PARANOIA', CLAIMS POLICE

Brazilian police spokeswoman Elen Souta alleged in a press conference Mr Hunt inhaled MDMA before swimming to the uninhabited Cotonduba Island, located off the coast of Rio, approximately three kilometres from Copacabana, after suffering a psychotic episode.

Ms Souta said Mr Hunt and an unidentified companion took the drug MDMA at his hotel, then went to a party at a club in Lapa, located in the centre of Rio.

At the party, they sniffed more MDMA and mixed it with vodka.

Overnight reports surfaced Mr Hunt had taken a number of
Overnight reports surfaced Mr Hunt had taken a number of "local drugs" before his disappearance. Photo: Find Rye Hunt/Facebook

It is claimed the pair were both hallucinating after taking the drugs, and were kicked out by security because the travellers thought other partygoers were trying to chase them.

TIMELINE OF MISSING AUSTRALIAN

Mr Hunt went missing on May 21 after he argued with Mr Sheppard over their next travel destination.

The travellers engaged in a verbal stoush over the pair's travel plans, and were at Galeao International Airport to book a flight to Bolivia.

Mr Hunt went to "cool off" after the May 21 disagreement but vanished after footage revealed he hopped on a taxi at the airport instead of meeting his mate to catch a flight to Bolivia.

It was 2:30pm local time in Rio.

The travelling duo had agreed to meet after half-an-hour, but in a strange twist Mr Hunt chose a new direction.

"They hadn't booked a flight; they went to the airport with the intention of buying a ticket and looked online for flights," Mr Hunt's sister, Romany Brodribb, told news.com.au.

But when a fight erupted between the pair over the destination, Mr Hunt stormed off and was never to be seen again.

"They had a disagreement. My brother, as much as I love him to absolute bits, if he gets a bit grumpy about something he needs a little time to cool off sometimes," Ms Brodribb said.

"I believe the disagreement had something to do with Bolivia and when they should be going and what they should do when they get there.

"He and Mitch had been travelling for seven weeks. It was the first disagreement they'd had in that time."

Ms Brodribb suspects the long-time friends had the disagreement, Mr Hunt "got into a grump", and Mr Sheppard suggested the pair "cool off" before meeting up in half an hour.

"I suspect that Rye probably was grumpy with Mitch and has left the airport and jumped," Ms Brodribb said.

After his disagreement with Mr Sheppard, CCTV footage captured Mr Hunt checking into a Copacabana apartment.

Mr Hunt's family confirmed he checked into the room an hour after leaving the airport, at approximately 2:30pm.

Almost three hours later, at 6:20pm, he left the apartment and hadn't been seen since the latest reports.

Authorities scoured Mr Hunt's Copacabana apartment and found his laptop, backpack, a camera and numerous other personal items.