Less than 4% of people arrested under the Terrorism Act 2000 were convicted of terrorism-related offences in 2009, new research has found.

Just eight people were convicted out of 207 arrests made under the act in 2009, according to Home Office statistics analysed by legal information provider Sweet & Maxwell.

In the 10 years since the act was introduced, of the 1,817 people arrested under it, 235 have been convicted for terrorist-related offences – less than 13%, the research found.

The Terrorism Act 2000 gave police new powers to arrest and detain suspects without charge.

Stephen Grosz, head of public law and human rights at London firm Bindmans, said: ‘The concern has always been that most individuals arrested under the draconian powers of the Terrorism Act 2000 could have been dealt with just as effectively under other areas of criminal law.

‘These statistics do suggest that the police may have been far quicker to make use of powers of arrest under the act than was necessary. Nobody should underplay the threat of terrorism, but the government and the police need to ensure that the civil liberties of a rising number of individuals are not being unnecessarily curtailed.’