[JURIST] Scotland Yard arrested four suspects [press release] in London on Wednesday in connection with the London transit bombings [JURIST report; JURIST news archive; BBC News timeline] on July 7, 2005 that left 52 people dead. Police arrested Mohammed Sidique Khan, Mohammed Shakil, Sadeer Saleem, and Waheed Ali on suspicion of the commission, preparation or instigation of acts of terrorism under the UK Terrorism Act 2000 [text]. According to the Metropolitan Police [official website], the arrests were part of a "pre-planned, intelligence-led operation."
Last month, British police arrested three men [JURIST report] in connection with the bombings. Those arrests were the first significant arrests in the bombings case. Al Qaeda officially claimed responsibility for the attacks on September 1, 2005, in a videotape which aired on al Jazeera TV. AP has more.