A SURGE in the number of plug-in vehicles on Scotland's roads is creating a bitter turf war over charging points, with some electric car owners demanding that hybrid drivers be banned from the free bays.

Karen Bain, a businesswoman from Uplawmoor in East Renfrewshire who has been driving an electric-only Renault Zoe for the past two years, said in recent months she is increasingly struggling to charge the vehicle when she is out because the charging bays are occupied by hybrid cars.

She believes that owners of the dual-powered vehicles, which switch to burning petrol or diesel once their battery goes flat, should be banned from hogging spaces needed by electric-only cars.

It is a problem which the Electric Vehicle Association Scotland, which represents electric vehicle drivers, has highlighted with Transport Scotland as an increasing gripe among its members.

Mrs Bain, 43, was on her way back from Stirling on Thursday when she visited Braehead shopping centre to charge her battery, which was nearly dead. However, she arrived to discover a hybrid vehicle already parked in the rapid charging bay - but not actually plugged in.

"It's the second time this has happened," said Mrs Bain. "The hybrid wasn't even charging, it was just using the space. It made me so mad. It's an abuse of the facilities, just because it's a good parking spot right next to Marks & Spencer."

A battery charge can take anything from 30 minutes to three or four hours.

Users of electric and hybrid cars are also entitled to free parking in some cities, including Glasgow. However, Mrs Bain said competition for spaces had forced her to pay to park elsewhere.

She added: "My gripe is that I feel priority should be given to electric vehicles and not hybrids - hybrids don't need to charge up when they're out, whereas electric vehicles do. We don't have a back-up. If I don't get my car charged, I can't get home."

The rapid charging points at Braehead were the first to open at a shopping centre in Scotland when they were installed in 2013, with Mrs Bain among the first customers.

However, the number of plug-in vehicles on the road has almost doubled since 2011 and rose by more than 40 per cent between 2013 and 2014 alone.

In 2014, one in every 100 new vehicles registered in Scotland was either a hybrid or pure electric - but hybrids still outnumber electrics by a ratio of around five to one.

Adrian Loening, a member and former chairman of EVA Scotland, said the battle over charging points had become increasingly contentious.

"You see it where you get free city centre parking in places like Glasgow that hybrid owners will park up next to a charger and just leave the car plugged in for hours," he said.

"We want to encourage people to take up electric cars, and plug-in hybrids are definitely a step in the right direction, but this is an issue that nobody really predicted.

"The criticism used to be that 'Transport Scotland spent all this money on a charge point and you never see anybody using it' - now there's a queue."

Transport Scotland has spent more than £10 million to date on electric vehicles and infrastructure, with 600 publicly available charge places across Scotland and 300 more in the pipeline.

A spokeswoman for Transport Scotland said: "We are building the ChargePlace Scotland network to accommodate an ever-increasing demand."