Detectives have been given a further extension to the amount of time they are allowed to hold and question six terrorism suspects. Four men from Derby, a man from Burton upon Trent and a woman from London were arrested on suspicion of offences under the Terrorism Act last week.
The North East Counter Terrorism Unit was later granted more time to question the six people. A further extension means the suspects can now be held until Boxing Day.
The four men from Derby are aged 22, 27, 35 and 36. The suspect from Burton upon Trent is aged 27 and the woman from London is 32.
Sources said the investigation was into a group believed to be working towards an attack, although a strike was not thought to be imminent.
