Scotland's councils should all rule out introducing the workplace parking levy, a trade union has said.

Unite has written to the 32 local authorities, calling on them to pledge not to bring in the controversial tax.

The parking levy, proposed in the budget deal agreed between the SNP and Scottish Greens, would give councils the power to introduce a charge on workplace car parking.

READ MORE: SNP's car parking levy may be worthy but is it workable? 

If introduced, the scheme would see employers pay an annual fee to the council for every parking space they provide for workers. Employers could then decide to pass on the cost to their staff.

Although environmental groups have welcomed the plan as a way to encourage people to use public transport and cut emissions, critics have condemned it for "taxing workers for turning up to work".

In the letter to councils, Unite's Scottish secretary Pat Rafferty urged them to oppose the devolution of the levy and rule out implementing the "regressive" policy.

Mr Rafferty condemned the lack of consultation over the plan, and said: "The ability for councils to set a workplace levy through car parking spaces is a desperate attempt to absolve the Government from the funding crisis they have presided over.

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"If implemented, we would have the ludicrous situation where we would have local authorities taxing workers for turning up to work.

"This would remove the pay increase that workers are currently fighting for off of them in an instance.

"We believe that the Scottish Government should be facilitating public ownership of the nation's buses and rail network, which would be a far better way to reduce car journeys through the provision of regular and affordable travel in Scotland."