The Home Office has been forced to apologise to 10 men placed under controversial anti-terrorist control orders after it linked them to the ricin plot in London, the Guardian has discovered.

In an embarrassing letter to the men, the government claims that it made a "clerical error" when it said the grounds for emergency restriction imposed on each of the alleged international terrorists was that they "belonged to and have provided support for a network of north African extremists directly involved in terrorist planning in the UK, including the use of toxic chemicals".