Havering’s top police chief has warned of the dangers of “laughing gas” after a teenager believed to have taken the legal high died at the weekend.

Borough commander Ch Supt Jason Gwillim also confirmed a rise in the number of empty canisters of nitrous oxide being found in parks and streets.

Police believe 18-year-old Ally Calvert had been drinking alcohol and ingested the gas at a party in Bexley on Saturday before he collapsed and died.

The legal high - inhaled using a balloon - can make people feel relaxed, euphoric and giggly, which has led to its nickname.

Abusing nitrous oxide can lead to oxygen deprivation resulting in loss of blood pressure, fainting and heart attacks.

It is not illegal to possess the gas, but selling it to under-18s in England and Wales is prohibited if there’s a risk they will inhale it.

Ch Supt Gwillam said: “It is not illegal to possess nitrous oxide but I would discourage anyone from using it.”

He also asked parents to speak to their children to warn them of the dangers.

Havering police are working with council partners to tackle the issue under new anti-social behaviour legislation and are to introduce Public Space Protection Orders in parks where the canisters are often found.

This will make it an offence to possess or consume “legal highs” and breaching an order will result in a fixed penalty notice being issued fining the person £100.

Sgt Charlie Routley, of Harold Wood Safer Neighbourhoods Team, said: “Following the tragic events highlighted in the news this weekend, I would discourage Havering residents from using this “legal high”.

“Nitrous Oxide abuse carries a risk to your health and personal safety. Just because it is not illegal to possess it, doesn’t make it safe to use in this way.

“In the coming months we will be working with our partners in trading standards to remind sellers that it is illegal to sell nitrous oxide to anyone under 18 years or to anyone who they suspect will inhale it.”

For further information on the dangers of inhaling nitrous oxide visit talktofrank.com