The synthetic chemical known as MDAI is being sold online in the UK, just two months after miaow miaow – or Mephedrone – was banned.

One website markets the drug – which is believed to be up to four times stronger than Mephedrone – as "bubble bath" and sells it for £20 a gram.

Last year miaow miaow became the fourth most popular drug in Britain behind cannabis, cocaine, and ecstasy.

It was believed to have been responsible for the deaths of up to 26 teenagers before it was classified as a Class B drug in April.

Analysts at the Psychonaut Research Project, an EU-funded organisation based at King's College London, which monitors the internet for new trends in drug abuse, said MDAI was the likeliest substance to replace Mephedrone.

They believe its chemical blueprint could soon be mass-produced by the Chinese manufacturers who flooded the UK with Mephedrone.

Cambotanics, based in Cambridge, sold miaow miaow online before the ban. It is now marketing the new high as bubble bath with free local delivery.

Its website states: "Please note that the chemicals sold here are NOT for human consumption."

James Brokenshire, the Tory Crime Prevention Minister, told The Sun the Government will fast-track bans on legal highs.

He said: "We are going to change our drug laws so we can respond quickly to emerging substances by introducing a temporary ban while we seek full scientific advice."