LONDON (AFP) - Four men were arrested on Thursday (July 9) in London and central England on suspicion of preparing terrorist acts, British police said.

Armed officers arrested three men aged 17, 27 and 31 at two addresses in east London, while unarmed colleagues detained a fourth 32-year-old man in the county of Leicestershire.

The Metropolitan Police said no shots were fired but the 27-year-old was bitten on the foot by a police dog during the arrests and had been taken to hospital.

His injuries were not believed to be serious, it added.

"All four men were arrested on suspicion of being concerned in the commission, preparation or instigation of acts of terrorism," the force said in a statement.

"Officers are currently searching the three addresses, and a search is also underway at a fourth address in east London as part of the investigation."

The Met said it had been assisted by officers from East Midlands Counter Terrorism Policing and Leicestershire police force in what it called a "proactive investigation".