Thousands of people across the UK may have been stopped and searched illegally, figures released by the Home Office suggest.
Powers under Section 44 of the Terrorism Act were used in "error" after the proper authorisations were not given.
In one example, for April 2004, the Met Police stopped 840 people.
Dozens of other examples from across the UK have been uncovered before rules were tightened in 2008.
Police Minister Nick Herbert said administrative errors were to blame and has ordered an internal review of procedures.
The Metropolitan Police is also urgently considering what steps can be taken to contact the individuals concerned.
news.bbc.co.uk/1/hi/politics/10283701.stm