A taxi driver is among three people being questioned over the July 7 London bombings.
Mohammed Shakil, 30, along with Sadeer Saleem, 26, and Shipon Ullah, 23, are being questioned by counter-terror detectives in London on suspicion of preparation of terrorist acts.
The three, who were named by sources, are all understood to have links to the Beeston suburb of Leeds, where three of the 7/7 bombers also had strong connections.
On Friday magistrates gave Scotland Yard another week to question them.
Shakil and Ullah were arrested on Thursday lunchtime in the terminal building at Manchester Airport as they prepared to board a flight to Pakistan. Saleem was arrested a few hours later at his home in Leeds.
Their arrests were the first of any significance in the hunt for those who supported and financed the four 7/7 suicide bombers who killed themselves and 52 innocent people in 2005.
The Met Police spokeswoman said the warrants for further detention granted by City of Westminster magistrates would expire on Thursday March 29.
It emerged on Friday that Shakil was a taxi driver who recently handed in his notice, saying that he was going to Pakistan. Shakil, a father of three, worked for Gee Gee Cars, according to the firm's owner, Abdul Waheed.
Mr Waheed said Shakil had worked for his firm since just before Christmas and was a model employee.
