British police said they had arrested a 27-year-old man today as part of their investigation into an suspected attempt to bomb London's transport system last July 21.
The man was detained by officers in the Kensington area of west London "on suspicion of the commission, preparation or instigation of acts of terrorism" relating to last year's alleged bomb plot.
Searches are now being carried out at two houses in west London and one business address.
The suspect has been taken for questioning to a central London police station.
Police say four men tried to set off bombs on three underground trains and a bus in the capital on July 21, but that their devices failed to detonate.
A fifth man is accused of dumping a device in park.
The suspected plot came just two weeks after four bombers killed themselves and 52 others in attacks on London's transport system.
Five men have appeared in court accused of planning to carry out attacks on July 21 and their trial is due to start in September. Numerous others have been charged in connection with the case.
A police source said the man arrested today was not thought to be involved in the planning but to have played a role after the alleged attacks took place.