A hefty price tag and uncertainty over battery costs are preventing drivers switching to electric cars, London Assembly members heard today.

The eco-friendly vehicles are double the price of conventional petrol or diesel cars, the Assembly’s environment committee was told.

Plans to develop Boris Johnson’s idea for a London electric network have been short-circuited because of unknown costs of battery packs—estimated at �10,000—putting off potential buyers.

The Assembly’s environment chair Murad Qureshi said: “The Mayor will have to work hard to convince Londoners there is a strong case for going electric if they are to make the switch.”

The Mayor’s environment director Kulveer Ranger acknowledged the ‘cost’ issue, but insisted vehicles are “getting cheaper” as more are developed.

Boris Johnson was trying to “create the environment for a market hungry for electric vehicles,” the environment director claimed.

But it was too early to estimate how many will be on London’s streets by 2013. He hoped next year’s London Olympics would be a chance for manufacturers to ‘showcase’ electric cars.