LONDON, July 8 (Xinhuanet) -- London's police chief said on Friday there was still no evidence that Thursday's terror attacks on the capital had been carried out by suicide bombers.

    "We have absolutely nothing to suggest this was a suicide bombing attack although nothing at this stage to rule that out," Head of London metropolitan police Ian Blair told a press conference.

    London's underground stations were hit by four bomb attacks at the rush hour on Thursday morning, which killed at least 50 peopleand injured 700.

    The attacks, the deadliest ever carried out on London in peacetime, coincided with a summit of the Group of Eight in Gleneagles, Scotland.

    Blair said efforts were still being made to establish the precise number of deaths from the blasts on three subway trains and one double-decker bus. Police said on Thursday that 35 people died on subway trains.

    Assistant Commissioner Andy Hayman said forensic investigationssuggested each one of the devices used in the attacks had probablycontained less than 10 pounds (4.5 kilograms) of high explosives.

    Hayman said that the explosive devices, due to their small sizes, could have been carried to the explosion sites with backpacks.

    "We do believe that each device put on the Tube trains was put on the floor of the carriages," Hayman said.

    The police commissioner also said it was possible that an active terror cell was still intact and capable of another attack.

    "We must remain vigilant," he said. Enditem