Electric vehicles could be banned from using bus lanes – because there are too many of them.

Nearly all the 2,700 sold in Norway are in the Oslo area and one of the perks of ownership is being allowed to travel in bus lanes.

"It is positive that we are increasing the volume of electric cars on the roads, but at the same time it is important for the environment that we have efficient public transit," Ivar Christiansen from the Public Roads Administration told state broadcaster NRK.

He said the increasing volume of electric cars in bus lanes is causing access problems and delays for public transit.

"I am worried that we are moving close to a ban on electric cars in bus lanes in certain places, Christensen tells NRK.

No ban can come in force until after 2017, the date already agreed by Oslo for the bus lane perk to remain.

"The government has decided that car owners can keep the advantages that come with buying, owning, and using an electric car as long as possible. We have no plans of changing that," Christiansen said.

But his department will monitor the situation closely as well as looking at other measures to improve the flow of public transport.

Norway has encouraged the use of electric vehicles for many years with tax and usage benefits, and that policy has seen strong take up of zero emission cars.

National and local governments in the Nordic nation have reduced VAT to zero, installed electric car only car parks and allowed the use of bus lanes to encourage Norwegians to switch to zero emission cars. To cope with the huge growth in the uptake of EVs, the council in Oslo has recently increased their charging point installations from 100 per year to 200 per year for the next four years.