Security Threat Fear Over Mobile Blackspot Plan

New laws which would force mobile firms to improve coverage in signal blackspots could threaten national security, the Home Secretary has claimed.

Theresa May has raised concerns over the plans to force companies to allow users to switch between networks if a signal is not available in a "national roaming" policy.

It would work in a similar way to the way roaming between networks does abroad.

However, Mrs May has voiced fears the move could have a "detrimental impact" on the work of police and intelligence agencies in accessing information "crucial to keeping us safe".

The Home Secretary has expressed her reservations in a letter to David Cameron, which was leaked to The Times.

It puts her on a collision course with the Culture Secretary Sajid Javid, who is unveiling his plans later.

Mr Javid made clear his intention to tackle the problem of poor mobile phone coverage, which affected a fifth of the country, when he took up his ministerial position in April.

Attempts to get agreement from the big mobile phone providers EE, O2, Three and Vodafone failed so Mr Javid is looking to legislation to force network sharing.

Mr Javid said: "I'm determined to ensure the UK has world-class mobile phone coverage as investment in infrastructure will help drive this government's long-term economic plan.

"It can't be right that in a fifth of the UK, people cannot use their phones to make a call. The Government isn't prepared to let that situation continue."

Other options being considered are:

:: Networks compelled to share equipment such as phone masts

:: Firms such as Tesco and Virgin allowed to sell packages offering access to all networks

:: Mobile phone firms forced to cover a certain percentage of the UK.

Mr Javid told Radio 4's Today programme: "The Home Secretary like every other member of the Government fully supports the strategy that we are setting out today."

Disclosure of Mrs May's intervention comes two days after the resignation of Lib Dem Home Office minister Norman Baker, who resigned after a series of run-ins.

Mr Baker said the Home Secretary was a "formidable woman" but accused her of putting obstacles in his way and regarding the Coalition as a Conservative government.

Shadow culture secretary Harriet Harman said: "Rather than briefing against each other as part of the ongoing Tory leadership squabble to replace David Cameron, Cabinet ministers should be making clear what the impact will be on 4G services for consumers and the emergency services, as well as any possible implications for national security and the fight against serious crime."

A spokesman for EE said: "We welcome the Government's consultation and an opportunity to examine the best way to improve voice coverage, as well as share our own plans to bring better voice call service to the UK. However, we have concerns about the feasibility of some of the proposals and their potentially damaging impact on consumers, competition and investment."