Alex Salmond is at the centre of the party's poster campaign

The move has signalled a battle for votes that will focus on personalities as well as policies.

The image of Mr Salmond, with the SNP's latest campaign slogan "First Vote for First Minister", will appear in ads across Scotland.

The campaign will be used on outdoor billboards and leaflets.

The SNP is hoping to make political capital from opinion polls which have shown the Banff and Buchan MP would be a more popular choice for first minister than Jack McConnell and the other party leaders.

Positive campaign

The party said placing Mr Salmond at the centre of its campaign was a "winning strategy" as it bids to bring in an extra 20 first-past-the-post seats at the Holyrood polls in May.

SNP campaign director, Angus Robertson MP, said: "All the available research tells us more and more Scots believe Alex Salmond is the people's choice for first minister.

"He stands for success for Scotland and Scottish families and has the fresh ideas to build a healthier, wealthier and safer nation.

"That's why the SNP is proud to have Alex Salmond front and centre in our positive campaign."