Authorities said they are trying to determine whether the apartment in Leeds, England, was used for meetings, storing chemicals or making the bombs used in the "7/7" bombings that killed 56 people and injured more than 700, unidentified sources told The Daily Telegraph.

In the years since the bombings, anti-terrorism officials have found bomb factories in the Hyde Park and Chapeltown areas of Leeds. The new site is a one-bedroom apartment in the Harehills area of North Leeds, about 3 miles from the first two and across the city from the Beeston neighborhood where three of the suicide bombers grew up, the Telegraph said.

One Harehills resident said police knocked on doors showing photographs of men, one of which he recognized as the bombers' alleged ringleader Sidique Khan. The unnamed resident told the newspaper the officers showed him several photos, asking if any of them had lived in the area.