British police say they have detained 14 men in anti-terrorism raids in south and east London, as well as two others in the city of Manchester.
Authorities say the arrests late Friday and early Saturday were not linked to the reported plot to bomb trans-Atlantic airliners.
Police have not revealed what the suspects are believed to have done, but they say the men were arrested as part of an investigation into terror training and recruitment. A British radio report says 12 of the arrests took place at a crowded Chinese restaurant that is popular with the Muslim community.
Police are continuing to search houses in London and an Islamic school in a village south of the capital.
Police also say the Manchester arrests were not related to the London ones.
The head of the London police department's anti-terrorism unit, Peter Clarke, said Friday that authorities are monitoring thousands of British Muslims and others who might be potential security suspects.
Some information for this report provided by AFP, AP and Reuters.