Electric cars which charge wirelessly could soon be on the roads, after Qualcomm announced it will begin tests in London.

Wireless charging would allow vehicles to park and fill their batteries without having to plug in a cable - even while still being driven.

The power would transmit using inductive charging, where energy is transferred using electromagnetic fields.

The technique is already common in many smaller gadgets, but has not been rolled out in cars partly because it is considered to be less efficient, and more costly.

But Qualcomm says that the "marginal" downsides of lost energy are compensated by the tech enabling more people to use electric vehicles.

It will start the first trials with Delta Motorsport in the second half of 2012.

The wireless system will be used in its Delta E-4 Coupe electric vehicles, and will be supported by government agencies and "private sector enterprises".

The aim is to test how the tech works in practice, and how commercially viable it might be.

"Rigorous user testing in the London trial will help us better understand future EV engineering challenges," said Nick Carpenter, technical director at Delta Motorsport.

A second round of tests will be carried out with Renault in 2013.