Newport Police Community Support Officer Andy Hudson said that they had dealt with a group of young people reported using the gas in the Queen Elizabeth II Park in Church Aston.
He said they had caught up with the youths shortly afterwards and had been voluntarily handed a large cannister of nitrous oxide by one present.
Following the incident, PCSO Hudson has warned people about the dangers of using of nitrous oxide.
He said: "On Sunday, August 28, Newport Safer Neighbourhood Team received reports of anti-social behaviour (ASB) including the use of nitrous oxide, also known as laughing gas, at the Queen Elizabeth II Park in Church Aston.
"On arriving at the park, a group of young people were seen leaving the area but were located nearby soon after.
"One of the individuals was found to be in possession of a large cannister of nitrous oxide which was voluntarily handed to police officers.
"Three of the individuals have been dealt with by way of ASB interventions."
PCSO Hudson added: "Although nitrous oxide has many legal uses, it is illegal when sold as a psychoactive drug.
"When the substance is inhaled, it can cause the user to have hallucinations.
"Repetitive use of the substance has been known to cause death in some cases and so we encourage parents and guardians to be aware of the dangers of the illegal use of nitrous oxide."