A man was arrested in Shoreditch last night after allegedly being found with five bags of laughing gas canisters.

The haul was found in the trendy east London quarter by two Hackney police officers on patrol.

Scotland Yard said a 29-year-old man was arrested on suspicion of harassment and taken to a north London police station for questioning.

Laughing gas is one of a number of so-called "legal highs" that could be outlawed by Theresa May's Psychoactive Substances Bill, revealed last week.

Under the bill, anyone caught selling laughing gas as a recreational drug could face up to seven years in prison.

The gas, chemical name nitrous oxide, can still be sold for "legitimate" use, according to the Home Office, but its sale and use as a psychoactive chemical is banned.

Those legitimate uses include blowing up helium balloons and preserving whipped cream.

Ahead of the bill, a dispersal zone was introduced in south London last year to stop people inhaling laughing gas as neighbours had complained of users' antisocial behaviour.

Drugs website Talk to Frank warns that, while laughing gas induces a feeling of euphoria, it also carries a risk of suffocation.

"There is a risk of death as a lack of oxygen can occur when using nitrous oxide," the site says. "This risk is likely to be greater if the gas is consumed in an enclosed space or if a substantial amount is rapidly used."

Critics of the proposed law, which bans anything that alters brain function, have accused it of ambiguity. Exemptions include products such as chocolate, coffee and alcohol.

Previously the government had been forced to individually name substances in legislation if it wanted to ban them - something supporters of the bill say made it hard to keep laws up-to-date.