The price of petrol will fall by 10 pence a gallon under SNP plans promoted by party leader John Swinney on Wednesday.

Launching a new poster to promote the campaign, Swinney said his party would be cutting 2.2 pence from the price of a litre of fuel, the equivalent of 10 pence off a gallon.

The reduction would be the start of a process to reduce Scotland's fuel taxes to the European average, the SNP announced.

"It is utterly absurd that in oil-rich Scotland, we pay the highest fuel prices in the western world," Swinney said.

He accused Labour of penalising Scottish drivers and promised the SNP would introduce a "fair and honest" taxation system based on ability to pay.

Maintaining the attack on Labour, the SNP's defence spokesman in the Scottish parliament, Colin Campbell, committed his party to maintaining guaranteeing the future of all six Scottish regiments, following press reports that the Black Watch might be axed.

"There has always been a strong traditional geographical link between regiments and communities in Scotland, and it is vital to both morale and recruitment that this continues," said Campbell.

Only a strong SNP contingent in Westminster would stand up for Scotland's interests in London, the nationalists claimed.