Plans to introduce mobile phone coverage on the London Underground in time for the 2012 summer Olympics have broken down as the Tube's antiquated network of narrow tunnels proved too difficult to connect in time.
Britain's four operators had been working with the Chinese telecoms provider Huawei and others to extend coverage on to the underground trains and stations in time for the Games which begin in July 2012.
However, the narrow, low and often hot nature of the tunnels combined with a lack of space at stations meant the area was hard to adapt.
A source familiar with the project said as a rough rule it was 10 times more expensive to put an antenna on the tube than it was to put one in a building.
"We are grateful to the companies who explored the possibility of getting full mobile coverage on the Tube, although disappointed the genuine problems encountered could not be overcome on this occasion," a statement from the Mayor of London said.
The operators and Huawei had agreed to examine the idea even though there was no public money for the project. The mobile operators were willing to pay for the networks to be installed while Huawei had offered to donate part of the equipment.
The operators -- Vodafone, Telefonica's O2, Everything Everywhere and Three UK -- have already spent several millions of pounds on the project.
"As a group, we will continue to positively explore all other avenues available to us in order to provide a service at a later date," they said in a joint statement.
A spokeswoman for the Chinese group said it was always open to any potential underground mobile network project in the future.
Plans for a major expansion of wi-fi coverage in Tube stations in time for the Olympics will not be affected.