UK drugs policy has “done nothing but go backwards” in the last decade, according to a former senior Westminster adviser.

Professor David Nutt was dismissed from his post as a chair of the Advisory Council on the Misuse of Drugs by then-home secretary Alan Johnson after claiming that alcohol and tobacco were more harmful than illegal substances like cannabis and LSD.

Ten years later, he says the Misuse of Drugs Act is “failing in its legal duty”.

The comments came in a talk at King’s College, London, as the Scottish Affairs Committee prepares to publish its delayed report on problem drug use in Scotland.

Drug laws remain reserved to Westminster, and despite cross-party calls for a new approach to tackle Scotland’s rising drug deaths, the UK Government has declined to make changes.

This includes any moves to amend legislation for the creation of a legal drugs consumption room in Glasgow, which has in the past year experienced some of the country’s worst drug-related problems.

Almost 1200 people suffered drug-related deaths in Scotland last year, with fatalities concentrated in the Greater Glasgow, Lothian, Lanarkshire and Tayside health board areas.

The level is almost three times that of the UK as a whole and higher than that of any other EU country.

Nutt, who backs safe injection rooms, blamed successive UK governments for a “litany of failure” and said “very little has changed” since 2010 research named alcohol as the “most harmful drug in the UK”.

And he warned it was “very likely” the UK will soon endure a rise in deaths from fentanyl, a powerful opioid used as pain medication which is sometimes mixed with other drugs like ecstasy or sold instead of this by dealers.

A report on the Health and Social Care Committee’s inquiry published last week – to which Nutt gave evidence – found the country’s position on drugs was “clearly failing” and called for a “radical new approach”.

Nutt said decriminalisation, which is favoured by the SNP, “would be a good start” and called on the “two major parties” at Westminster to “grow up” and talk seriously about drugs.

Last week, the UK Government said it “has no plans to decriminalise drug possession”, saying this “would not eliminate the crime” or address the harms.

Yesterday a spokeswoman stated: “We are committed to reducing the use of illegal drugs and the harms they cause and the Home Office has commissioned a major independent review to examine these issues.”

Meanwhile, Nikki Holland, director of investigations at the National Crime Agency, says “phenomenal” amounts of illegal substances are being smuggled into the UK, despite massive seizures by officials. This includes a near-1.3 tonnes heroin haul in August.

Holland said: “If we double the size of the agency, we might get nearer to choking that supply.”