The Home Office has admitted that thousands of stop-and-searches undergone under Section 44 of the Terrorism Act 2000 were illegal, as the powers were used in error. According to the Home Office, which made the revelations today, 14 police forces around the country used the powers in 40 operations that were not approved by the Home Office or extended beyond the conventional 28-day period.

In a ministerial statement, released by the Home Office, Security minister Baroness Neville-Jones informed the house of the Metropolitan Police Service had undertaken work in relation to a request for information under the Freedom of Information Act concerning authorisations for the section 44 stop and search powers," she says. "In the course of reviewing their section 44 records, the MPS identified an authorisation from April 2004 which had not been confirmed by a Home Office Minister within the statutory 48 hour deadline for confirmation. Subsequent investigations revealed that approximately 840 were stopped and searched in the relevant area during the period of the invalid authorisation. The MPS are urgently considering what steps can reasonably be taken to contact those individuals involved."

In order to use stop-and-search powers, chief constables must request authorisation from the Home Office, which must respond under a 48-hour deadline and can only grant the powers for 28 days. At the end of the 28 days, a chief constable must seek another authorisation.

As a result of this discovery, says Baroness Neville-Jones, the Office for Security and Counter Terrorism in the Home Office "undertook a review in May 2010 of all section 44 authorisations since the Terrorism Act came into force on 19 February 2001, in the course of which a number of other errors came to light. I have to inform the House that it appears that stop and search powers have been used unlawfully by a number of police forces on a number of occasions."

She adds: "The Home Office has written to each of the police forces concerned to alert them to these errors and those forces are now in the process of assessing how many individuals were stopped and searched in the periods of invalid authorisations. They will do their best to contact those involved. To summarise these errors, on 33 occasions authorisations were specified to be for 29 days, and 2 occasions when the authorisations were specified to be for 30 days, whereas the statutory maximum period is 28 days. In addition, there was 1 further case (as well as the MPS incident in April 2004) where Ministerial confirmation for the authorisation was not provided within the statutory 48 hour deadline. All of these cases appear to have been as a result of administrative errors which were not identified at the time by either the police or the Home Office."

The stop-and-search powers were introduced in February 2001 to help deter terrorism. However, in recent years, Section 44 has been increasingly used against photographers - amateurs and professionals. The abuse  led BJP to file more than 100 Freedom of Information requests with all constabularies around the country in a bid to inform photographers on whether they can, legally, be stopped. Read our Special Report "FoI requests show extent of Section 44 use" published on 21 December 2009.

The revelations will not help the Home Office's case in front of the European Court of Human Rights, which, earlier this year, found Section 44 to be illegal. The European Court stated that the powers lack proper 'safeguards against abuse'.

The court was hearing the case of Kevin Gillan and Pennie Quinton, who were both stopped during a London-based arms trade show on 09 September 2003. The police were 'acting under sections 44-47 of the 2000 Act, while (the two were) on their way to a demonstration close to an arms fair held in the Docklands area of East London'.

The court has found that the two protesters' rights had been violated under Article 8 of the European Convention on Human Rights. 'The Court considered that the use of the coercive powers conferred by the anti-terrorism legislation to require an individual to submit to a detailed search of their person, clothing and personal belongings amounted to a clear interference with the right to respect for private life,' the European Court found in its judgment. Read our full report "State rebuked over Section 44" published on 20 January.

Theresa May, the new home secretary, has already pledged to review the use of the controversial powers. However, such review is unlikely to happen until the European Court reaches a decision on the Home Office's appeal to its 12 January ruling. Read "UK Government appeals Section 44 European Court ruling" published on 13 April.