British law enforcement and intelligence services have helped draw up an extra-judicial ‘kill list’ to assassinate the world’s most wanted terrorists and drug smugglers in foreign countries.

The sensational claims, which raise disturbing questions about Britain’s involvement in the targeting of aircraft and drone strikes, will be revealed in a 50-page report by the Reprieve human rights charity to be published tomorrow.

It will state that the UK has been a key, long-standing partner in America’s ‘shoot to kill’ policy in Afghanistan and Pakistan, targeting not only alleged terrorists, but also supposed drug traffickers, and earmarking them for drone and missile strikes – often on the basis of unsubstantiated ‘intelligence’ which has never been tested in court.

Although the top secret ‘kill list’ has been in existence for years and is continually revised, Britain’s contribution has never been sanctioned by Parliament.

The startling evidence, drawn from leaked official documents, reveals the two agencies involved are the electronic eavesdropping organisation GCHQ, and the Serious and Organised Crime Agency (SOCA), now rebranded as the National Crime Agency (NCA).

British law enforcement and intelligence services have helped draw up an extra-judicial ‘kill list’ to assassinate the world’s most wanted terrorists and drug smugglers in foreign countries

Britain abolished capital punishment in its courts in 1965, but the report says its findings show that ‘Britain now supports the death penalty without any trial at all’.

The leaked documents reveal:

The assassination list was known as the ‘Joint Prioritized Effects List’;

Alleged drug traffickers, including 50 Afghans, were first put on the kill list in 2009;

SOCA and GCHQ have worked closely with US secret intelligence agencies to identify targets;

Britain’s Joint Narcotics Analysis Centre in London helped direct strikes in Afghanistan;

The targets’ codenames include obscure Scottish towns and British rock bands, such as Judas Priest;

An innocent Afghan family was wiped out in a missile strike after one of the men was apparently mistaken for a member of the Taliban on the kill list.

Last night, Tory MP David Davis called for an urgent inquiry, saying: ‘The suggestion a British policing agency should provide intelligence to enable the deliberate killing of drug dealers challenges principles at the heart of British law enforcement. Lethal force is only authorised under British law when it is the sole option available to prevent the immediate loss of innocent life.

‘That an innocent family were killed is a terrible demonstration of what happens when we depart from our well- established standards. The Government must explain precisely what it has authorised and initiate an inquiry.’

Shadow Home Secretary Andy Burnham added: ‘This report raises extremely serious concerns and cannot be ignored. There must be no suggestion of collusion by the British authorities in actions of this kind. These allegations are not proven, but as they are so serious they must be investigated.’

In 2013, the list became the subject of a High Court legal action brought by Afghan bank executive Habib Rahman, whose father-in-law, two brothers and two uncles were wiped out by an air strike – killings which were not only unlawful, he argued, but the result of mistaken identity.

Zabet Amanullah, pictured with his children, was killed in a US-led air strike when he was mistake for a Taliban leader. His son-in-law claimed Britain was involved but a court said there was not enough evidence

The judge threw the case out in November that year, saying there was not enough evidence to support Mr Rahman’s claim of British involvement, which the Government had strenuously denied. At that time, the leaked documents behind the new report were still secret.

Interviewed in the Afghan capital last week, Mr Rahman recalled the moment on September 2, 2010, when he heard that his father-in-law, Zabet Amanullah, two uncles and his brothers, Faiz and Atiqullah, had been killed near the family home in Takhar Province.

They had been campaigning for parliamentary elections and were driving in convoy. Mr Rahman’s first thought was Mr Amanullah had been murdered by a local rival.

‘The Government had promised to support those who supported democracy,’ he said. ‘I never thought that they would be killed by the Americans or British.’

But gradually, in a series of phone calls from another, surviving brother, the truth sank in. ‘He said, “I found Atiqullah’s leg, his hand. I found Zabet’s body.” At first, they couldn’t find Miraj, one of my uncles, but then they found him under some soil. He was wounded and after a few minutes, he died.’

Almost immediately, the attack – which killed ten people – was condemned by Afghanistan’s then-President, Hamid Karzai.

It soon become obvious Mr Amanullah was not the intended target at all after the US-led ISAF coalition claimed it had eliminated Takhar’s Taliban deputy ‘shadow governor’, an Uzbek fighter named Muhammad Amin – who was still alive.

The intelligence blunder was the result of a mix-up over bugged mobile phone numbers. But it was not the reason why Mr Rahman tried to sue in London. The basis for his action was a 2009 US Senate Foreign Relations Committee report, which claimed SOCA was closely involved in the drawing up of the ISAF ‘kill list’ – known as the JPEL, the Joint Prioritized Effects List.

The startling evidence, drawn from leaked official documents, reveals the two agencies involved are the electronic eavesdropping organisation GCHQ

The report’s lead author, Douglas Frantz, a top aide to then-Senator (now Secretary of State) John Kerry, swore an affidavit supporting Mr Rahman’s lawsuit. It described how he had met with officials in Kabul, including a senior SOCA officer: ‘Military and civilian officials had provided information about the effort to combine law enforcement and military authorities in a program to identify drug traffickers…

‘People who met the specific criteria would be placed on the JPEL, which would subject them to arrest and possible killing. It is my understanding from the remarks made by the SOCA representative that… information collected by SOCA would be used in the compilation of the JPEL. The people on the JPEL would be subject to being captured or killed.’

Mr Frantz said there were about 50 suspected drug traffickers on the list in the summer of 2009. Although SOCA admitted working with other agencies in Afghanistan, it denied involvement in the JPEL, insisting it would only disseminate intelligence that might lead to someone being killed ‘where the target poses a significant and immediate threat to the lives of others’.

Mr Justice Irwin ruled this was ‘critically different from placing a person on a list for planned killing’ and dismissed the lawsuit.

Now, however, new evidence has emerged, the most important of which comes from the material leaked by Edward Snowden, who worked for GCHQ’s US sister agency, the NSA. First is a copy of the JPEL itself. Dating from 2010, it contains almost 700 names.

A member of the Afghan Narcotics Police

Second is an article from the NSA’s internal magazine, SID Today, classified as ‘top secret’ but seen by The Mail on Sunday. This makes the involvement of GCHQ and SOCA in drawing up the kill list explicit – and confirms Mr Frantz’s affidavit. The article describes the work of an NSA unit based in Atlanta, the Southwest Asia Narcotics Division. From May 2008, this ‘began providing real-time support to counter-narcotics operations, targeting processing laboratories, traffickers’ compounds and the traffickers themselves when they were on the move’.

The unit was not only interested in opium and heroin: among its biggest successes, it counted ‘the largest single drug seizure in history – 237 metric tons of hashish.’ (Hashish is now legal in several US states.)

It added the unit ‘and its colleagues at GCHQ has provided real-time intelligence to over 20 counter-narcotics operations, netting thousands of kilograms of drugs, detainees and weapons’.

But this wasn’t all. In 2009, the article went on, ‘narcotics traffickers were added to the JPEL for the first time, allowing them to be targeted for strikes. In October 2008, Nato defence ministers agreed narcotics trafficking networks were legitimate targets… due to the traffickers’ ties to the insurgency’.

This agreement – to which the UK was party, as a major ISAF ally – stayed secret. The consequence was the line dividing the ‘war on terror’ from the ‘war on drugs’ had become dangerously blurred, and drug dealers were now considered fair game for extra-judicial killing.

The Atlanta unit was ‘working closely with a number of colleagues’. And who might they be? ‘These were located at GCHQ, the Joint Narcotics Analysis Centre [in] London (JNAC), and the Interagency Operations Coordination Centre (IOCC) in Kabul.’

Intelligence channelled via JNAC to the IOCC was not only used to direct strikes in Afghanistan. The secret article stated that a convoy led by a ‘primary target’ named as Mullah Multan was hit by a strike as he drove from his home in Pakistan: ‘Though Mullah Multan survived the strike… he suffered the loss of over 3 tons of opium along with six of his cohorts.’

The article concluded, the Atlanta NSA unit was ‘saving lives and contributing to the Coalition’s ability to establish security throughout Afghanistan’ – over half of which, following ISAF’s departure in 2014, is back in Taliban hands.

A leaked version of the kill list from 2010 does not contain real names, only the codenames of 669 ‘objectives’ – ie targets. Some of these are culturally so British, however, it seems highly likely they were dreamt up by a British operative. Some are distinctly Scottish, for example, OBJ[jective] TAGGART, OBJ KIRN (a village in Argyll) OBJ BRECHIN and OBJ STILTSKIN (a Scottish rock band).

SOCA, now the National Crime Agency, is one of the organisations believed to be involved in the kill list

Others are more English, such as OBJ KINGSBURY (a London suburb) OBJ SLOANE, OBJ FAWKES and OBJ JUDAS PRIEST.

In September, David Cameron told the Commons that for the first time, UK citizens believed to be fighting with Isis in Syria were on a kill list. This later resulted in the death of Mohammed Emwazi, better known as Jihadi John. But targeted killing, Mr Cameron added, was ‘a novel departure’ for Britain. Few will mourn the loss of Emwazi. But in light of the classified US article, this looks like less than the whole truth.

Mr Rahman said: ‘From the beginning, we’ve been asking them to look at the evidence, but no one has listened. I feel completely disillusioned. It seems only those with power can get justice.’

Clive Stafford Smith, Reprieve’s director and the lead author of the new report, said he had spent much of his career trying to save prisoners on America’s death rows, ‘and so it’s very distressing Britain, which abolished the death penalty 51 years ago, now seems to believe in conducting executions without trials’.

He added: ‘There has got to be a serious inquiry, and the Government has to come clean. We keep getting into bed with America in violating human rights, as with Guantanamo and Abu Ghraib. They justify it as making Britain safer – but the reverse is always true.’

Mr Rahman agreed, saying the deaths of innocents in drone and air strikes only swelled the extremists’ ranks: ‘British prestige will be damaged. They are always raising their voices for human rights, but they have damaged human rights.

‘Daesh [Isis], the Taliban, Al Qaeda: these terrorist groups are the sons of these international or US actions. There were 10 victims in this incident and each of those have relations. Not everyone is like me sitting quietly. Definitely some will join terrorist groups to take revenge.’