Wireless phone transmitters will soon be installed in London's Underground system despite fears they could be used to set off a terrorist bomb.

Officials determined that presence of wireless transmitters is not a factor in the use of a cell phone to trigger a radio-controlled explosive device.

Cell phones were physically attached to the bombs that killed nearly 200 Madrid commuters in 2004. The bombs were set off by the phones' timer functions and not by their signal.

"The timer of a mobile phone operates independently to whether it is in a location that can receive a signal or not," a spokesman for the Underground told the BBC. "Therefore, the Tube would not be placed at any greater risk from that type of attack than it is now."

Officials contended that wireless communications underground would actually be a benefit in the event of emergency.

The Underground will conduct a two-month feasibility study on plans to place transmitters in four stations. The contract for the project will be awarded next year with service commencing in 2008.

Copyright 2006 by United Press International