LONDON: Police have confirmed that one international student and four British nationals had been detained under the Terrorism Act for allegedly plotting violence as world leaders gather in the UK capital for tomorrow's G20 summit.

A police officer, who confirmed the news with China Daily on Monday night, refused to elaborate on the detentions. But the anonymous officer added there would be a larger security operation surrounding the G20 event and related demonstrations as activists flood London.

The three men, aged 25, 19 and 16, and the 20-year-old woman - all of whom live in the Plymouth area - remain in custody, media reported.