Nearly 500 people have been arrested since a ban on so-called legal highs came into force six months ago, the Home Office has said.

Just four people have been jailed since psychoactive substances were outlawed at the end of May, but the Government said more are progressing through the courts.

The designer drugs, which produce highs similar to cocaine, cannabis and ecstasy, have been linked to hundreds of deaths and fuel anti-social behaviour.

They have increasingly become the drugs of choice for prisoners, and have been blamed for contributing to rising levels of violence in Britain's troubled jails.

Some 492 people were arrested in the six months after the legislation came into force on May 26.

Four people have been jailed including William Cook, 29, of Fernan Dell, Crownhill, Milton Keynes, who was handed three and a half years after being caught with hundreds of canisters of nitrous oxide - dubbed hippy crack - at the Electric Daisy Carnival, the Home Office said.

Some 332 shops across the UK have stopped selling the drugs while 31 head shops - which sell drugs paraphernalia - have closed down.

Home Office minister Sarah Newton said: "We banned new psychoactive substances because they are not safe, they can devastate lives and we will not tolerate them in this country.

"I am pleased to see the police making full use of the new powers, arresting dealers and ensuring they are punished with prison sentences which reflect the seriousness of this crime.

"At the same time as supporting law enforcement in tackling the supply of illegal drugs, we are also taking action to prevent the harms caused by their use - from educating young people about the risks to helping dependent individuals through treatment."

Legal Highs in Newcastle

In 2015, new psychoactive substances were involved in 204 deaths in the UK - up 25% from 163 deaths in 2014, the Home Office said.

Commander Simon Bray, the National Police Chiefs' Council's lead on new psychoactive substances (NPS), said: "The Psychoactive Substances Act fundamentally changed the way the police tackle the supply and distribution of these dangerous drugs.

"Across the country officers are using the full range of powers to enforce the law, and the figures released today highlight their commitment to reducing the availability of these harmful substances.