THE cost of spreading the word on Alex Salmond's plan for independence is £800,000 and rising, according to latest statistics.

That has been the cost of producing printed copies of the White Paper on independence and putting it out online - both of which have been done in very similar numbers.

Political opponents have criticised the exercise as public money that could have been spent elsewhere. Ministers argue it has been a triumph of democracy and voter engagement.

The White Paper has become an interesting document for political scientists. It is in its way a best seller, with huge downloads online and through the e-readers - the split between paper and electronic copies is almost 50:50.

Devolution Minister Nicola Sturgeon said: "The White Paper is the most comprehensive and detailed blueprint of its kind ever published, not just for Scotland, but for any prospective independent country.

"It is a landmark document, which sets out the economic, social and democratic case for independence, and provides the people of Scotland with the answers they need to make an informed choice on September 18 this year."

Liberal Democrat MSP Jim Hume said: "This is one holiday bestseller, which will quickly be consigned to the bargain bin.

"We all know that the SNP will say anything to achieve independence. What we didn't know is how much we are paying for them to say it.

"Taxpayers will be fuming that the Scottish Government has spent the equivalent of a lottery win on a document which fails to answer any of their basic questions on independence."

Scottish Conservative deputy leader Jackson Carlaw said the cost of the document "would be a considerable spend for a work of fact" but "the biggest ever taxpayer-funded investments for a work of fiction."