British police have been granted another three days to question the eight men arrested on Tuesday during anti-terrorist raids across the south east of England.
Officers can now hold the suspects, all British citizens and Muslims, under the Terrorism Act until Saturday afternoon, Scotland Yard confirmed.
The arrests came as police found half a ton of ammonium nitrate fertiliser, which they believe could have been used in a devastating blast, during 24 raids across south-east England.
The extension for the British detainees, granted by a court, came as a man was charged in Canada with helping terrorist activity in London.
Mohammad Momin Khawaja, 29, a software developer, appeared in an Ottawa court in shackles and a bullet-proof vest after his arrest by Royal Canadian Mounted Police on Monday.
Khawaja, a Canadian of Pakistani descent, is alleged to have "knowingly participate in or contributed to the activities of a terrorist group and to knowingly facilitate a terrorist activity".
The offences allegedly took place "on or between November 10, 2003 and March 29, 2004 at or near the City of Ottawa, in the Province of Ontario, and at or near the City of London, England".
He recently travelled to London but claims he was meeting a prospective bride. He was remanded in custody until Friday.
His brother Qasim insisted he was innocent, adding: "They are looking for something that does not exist. They want to fabricate or create it somehow."
In England, more than 700 police officers were involved in yesterday's operation, code-named Crevice. The eight suspects, aged 17 to 32, were held on suspicion of "being concerned in the commission, preparation or instigation of acts of terrorism".
PA