Right by the store entrance - a temptation for many drivers

Duncan McNeil, who has called for "space invaders" to be fined, claims one in five bays in supermarkets and other private places are hijacked.

Offenders at present can be prosecuted on a public road, but not when private parking is involved.

Mr McNeil is supported by fellow-MSP Johann Lamont, who demanded a "comprehensive awareness" campaign.

Perhaps it is time to go beyond appealing to people's better nature and start appealing to their pockets Duncan McNeil MSP

He said: "Disabled drivers from across my constituency express to me their frustration, not just at the bone-idle and selfish 'space invaders' who abuse disabled parking space, but at the apparent reluctance of car park owners to enforce their own parking policy."

The MSP for Greenock and Inverclyde added: "If we cannot make the present system work, perhaps it is time to go beyond appealing to people's better nature and start appealing to their pockets."

Ms Lamont wants a probe into rules governing the abuse of parking bays outside the homes of disabled drivers.

Baywatch probe

"The accounts of intimidation and neighbourhood conflict which some of my most vulnerable constituents relate to me are, frankly, deplorable," she said.

The MSP for Glasgow Pollock added: "Their only crime is to be sufficiently infirm to require a disabled parking space outside their homes."

Campaign group Baywatch monitored parking at more than 800 stores owned by the 'big four' supermarkets - Sainsbury's, Asda, Safeway and Tesco in January.