British police have detained three people at Heathrow Airport under the nation's anti-terrorism act, but officials did not connect the arrests to the London bombings.
At a news conference Sunday, a senior police official, Commander Brian Paddick, called the arrests routine and said it would be inappropriate to draw any direct link with last week's terror attacks.
The official said police have so far received 1,700 calls to a special anti-terrorist tip line. Authorities have asked people to send in cell-phone camera images or other information that might help identify the bombers.
Meanwhile, crime scene and recovery crews continued working in a narrow, dark subway tunnel near Russell Square Sunday. The official count of fatalities remained at 49 but is expected to rise as workers search through the debris.
Some information for this report provided by AP, AFP and Reuters.