Fears that the government’s anti-radicalisation strategy, Prevent, is used as a “trawling exercise” will be reinforced by revelations that police forces have been storing personal details of all those referred to the scheme in a database without the knowledge or consent of the individuals involved, the shadow security minister has said.

The National Police Prevent Case Management (PCM) database is managed centrally by national counter-terrorism policing headquarters and is compiled by all police forces across the England, Wales, Scotland and Northern Ireland, according to documents sent to the human rights group Liberty and seen by the Guardian.

The directory includes personal details of the individuals referred to Prevent and the reasons for the referral, and both are added without notifying the person involved.

The stated aim of Prevent, a voluntary programme, is to divert people from terrorism before they offend, and crucially it deals with individuals who have yet to cross the criminality threshold. About nine in 10 referrals result in the individual leaving the process without facing further action or being signposted to alternative services.

Quick guide What is Prevent? Show Hide What is Prevent? Prevent is one of the four “Ps” of the government’s counter-terrorism strategy, along with Pursue, Protect and Prepare. It was created by the Labour government in 2003 and its remit was widened by the coalition government in 2011. Its stated purpose is to safeguard and support those vulnerable to radicalisation and to stop them from becoming terrorists or supporting terrorism. How does it prevent people from becoming terrorists? Individuals suspected of being vulnerable to radicalisation can be referred to police for further assessment. One of the most controversial aspects of Prevent was the statutory duty introduced in 2015 on schools, NHS trusts, prisons and local authorities to report concerns about people who may be at risk of turning to extremism or terrorism. Once referred, the individual will be assessed to see whether or not further intervention is required. If an individual is assessed to be vulnerable to radicalisation, they may be offered support through the Channel programme in England and Wales, or the Prevent Professional Concerns (PPC) programme in Scotland. This is a voluntary process. Between 2017 and 2018, a total of 7,318 individuals were subject to a referral but only 394 were escalated to the Channel process. Why is Prevent controversial? The most common criticism levelled at the Prevent strategy is that it disproportionately impacts people of Muslim faith or background and inhibits legitimate expression. There have been numerous reports over the last 15 years that have fuelled this perception: an eight-year-old questioned by Prevent after his teachers mistook his T-shirt slogan for Islamic State propaganda, a 17-year-old referred because he wore a “Free Palestine” badge to school and a student of counter-terrorism questioned after an official spotted him reading a textbook entitled Terrorism Studies. The Prevent brand has been labelled “toxic” in parts of the Muslim community. But senior policing and security figures continue to back Prevent. In September 2019 the UK’s most senior counter-terrorism officer, Neil Basu, vigorously defended the programme in a speech in Israel, while security ministers and former home secretaries have insisted it has saved lives. Jamie Grierson, Home affairs correspondent

Police chiefs said the database was legally compliant, and recording referrals ensured accountability and allowed forces to monitor “when vulnerabilities are increasing”.

But Nick Thomas-Symonds, the shadow minister for security, said the revelations raised many serious questions, including the extent of the database, how the information has been used and by whom.

“It will reinforce the worst fears of many campaigners concerned that Prevent can be used as a trawling exercise and that people, including children, who have committed no crime are regarded as suspects,” he said.

“This underlines the need for a comprehensive, independent review of the Prevent programme, and the government’s appointment of Lord Carlile as a reviewer falls well short of that. Labour in government will conduct a robust review of Prevent and formulate a counter-terror programme which can command the confidence of all communities across the country.”

Any rank of police officer or staff can access the database but users must be Prevent practitioners, who are vetted and given training prior to access. Chief constables are the designated data controllers within their respective forces.

External agencies are able to request information from the database. It is not known how many requests have been granted or to whom.

Forces that responded to Liberty’s request for information said all referrals were added at the time of receipt, and official statistics show 21,042 individuals have been referred in the three years to March 2018 alone.

In the most recent year available, 2017-18, a total of 7,318 individuals were subject to a referral, of whom 3,096 (42%) left the process requiring no further action and 3,466 left the process and were signposted to alternative services.

The majority – 4,144 (57%) – were aged 20 years or under. Within this figure, 2,009 were under 15 and 2,135 were aged 15 to 20.

A spokesman for the National Police Chiefs’ Council said: “The public would expect the police to maintain professional records of those individuals referred for support as potential victims of radicalisation. This is no different to the way we record other forms of supportive safeguarding activity such as child sexual exploitation, domestic abuse or human trafficking.

“Good records ensure we are accountable, allow us to understand when vulnerabilities are increasing, and ensure we act consistently and proportionately, only taking action in those cases where our support is necessary. If we did not maintain proper, legally compliant records, the public would rightly have far less confidence in the police.”