Police have issued a safety warning to the public after a man was seen huffing petrol from inside a dryer at a Manurewa laundromat last Sunday.

In disturbing scenes, local customers at the 24-hour self-service facility witnessed a man sitting with his body inside a dryer, believed to be inhaling petrol from a jerrycan.

The same man was also seen asleep in the dryer by another customer who was concerned at his actions.

One witness posted to social media saying they were concerned for the safety of those in the laundromat but that many customers were too scared to approach the man.

"Me and my son were taking our clothes to the laundromat to dry. I hear some voices and yelling, I got a big fright. A boy sniffing gas sitting in the dryer.

"I yelled at him, 'what are you doing?' He just stared at us. Everyone was too scared to tell him to leave. What is this world coming to ... He could blow that place up with gasoline inside a laundromat."

Another person claimed the man had also been seen asleep in the same dryer just hours earlier.

Police confirmed to the Herald they were aware of the incident and have called on members of the public to call emergency services next time.

"Police are aware of this incident, however no report has been filed nor did we attend the incident.

"Our advice to people who may witness this type of behaviour is to call an ambulance in the first instance and ensure they get the appropriate medical treatment."

The Herald contacted the laundromat but the owner declined comment, however, the landlord said he was very concerned and would be doing what he could to prevent this sort of behaviour.

Locals have since taken to social media calling for the young man to receive help, saying the incident was not only highly dangerous but that it was extremely sad to see another person in such a bad state.

"That is actually so sad that some young person's life has gone so far the wrong way that [they thought] this was a good idea," one said.

Another wrote: "Why didn't someone call ambulance or police? He needed to get out of there not just for the safety of others but for his own health. Sad that people get to this situation, yet others can turn a blind eye."

Worksafe's website advises people not to use electric equipment near petrol, saying a spark from the electronics could ignite the fuel.

"Breathing petrol fumes is dangerous. Exposure to vapour concentrations can cause respiratory irritation, headache, dizziness, nausea and loss of co-ordination," it said on their website.

"Higher concentrations may cause loss of consciousness, cardiac sensitisation, coma and death resulting from respiratory failure."