The plan to have a 3G mobile network in the tunnels of the London Underground in time for the 2012 Olympics has been scrapped due to escalating costs.

Back in November last year reports broke of a supposed £150 million deal between TFL and the big four networks, with talks of a conclusion being "just weeks away". It's understood that Boris Johnson had given his backing to the scheme and Huawei was in place to offer up the equipment needed for the underground coverage.

However, despite Vodafone, O2, Everything Everywhere and Three apparently already spending "millions" on the plan, it's now been ditched.

"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.

"We are grateful to the companies who explored the possibility of getting full mobile coverage on the Tube, although disappointed that the genuine problems encountered could not be overcome on this occasion," a statement from the Mayor of London said.

It's not a complete tech black out for the Tube though, earlier this week we told you how TFL is inviting bidders for a tube-wide Wi-Fi contract, following a successful trial at Charing Cross.

It's expected that Wi-Fi on Tube stations will be ready in time for the Games.