Drivers who break down on over 4,500 miles of Britain's roads cannot call for help because there is no mobile phone coverage, a motoring charity has warned.

A study by the RAC Foundation found 4,561 miles of road - representing about 2% of the entire network - do not have any 2G coverage, which is the minimum required to make a call or send a text.

These stretches of road include the A149 in East Anglia, A591 in Cumbria, A93 in Scotland and A494 in Wales.

A further 28,975 miles have partial 2G coverage, meaning only certain mobile operators provide a signal.

Motorists who rely on their smartphones to access the internet for route planning and to check for congestion could get into difficulty on 14,554 miles of road (around 6%) with a complete absence of 3G coverage, the study found.

An additional 111,679 miles - some 45% - is only covered for 3G by some operators.

In terms of 4G, more than half (56%) of the road network has no coverage, while over a quarter (27%) has only partial coverage.

The research was based on analysis of data published by communications regulator Ofcom.

RAC Foundation director Steve Gooding said: "There are thousands of miles of road along which you would not want to break down or have an accident because calling the RAC, the emergency services or even home wouldn't be an option.

"Even where there is partial network coverage it might not be from your network provider.

"The concepts of connected cars and drivers is at the heart of much thinking about how we might make our travelling lives easier. But the best ideas in the world will fall at the first hurdle if there are no bars on the phone."

The RAC Foundation found the local authority areas with the most miles of road lacking any mobile signal are:

:: 1. Highland (452 miles of road with no coverage).

:: 2. Powys (437 miles).

:: 3. Argyll and Bute (293 miles).

:: 4. Cumbria (252 miles).

:: 5. Devon (243 miles).

:: 6. Dumfries and Galloway (237 miles).

:: 7. North Yorkshire (231 miles).

:: 8. Scottish Borders (226 miles).

:: 9. Gwynedd (172 miles).

:: 10. Ceredigion (156 miles).