The move comes as the party seeking independence for Scotland continues its battle with Labour for votes north of the border.

The Prince will meet Mr Salmond during Scottish engagements in the coming week.

Balmoral: Could be the venue

But despite the SNP's recent strong showing in the polls, the Palace has played down suggestions that the meeting represents anything other than a normal duty for the heir to the throne.

A spokeswoman said: "The prince, like other senior members of the royal family, meets a wide variety of people from across the political spectrum to ensure that the Royal Family is in touch with developments in public opinion."

Mr Salmond has been in contact with the Royal Family before when he attended the funeral of Diana, Princess of Wales.

The prince is believed to have met leaders of Welsh Nationalists Plaid Cyrmu in the past in his capacity as Prince of Wales.

Slimmed-down monarchy

Mr Salmond is likely to brief the prince on his party's views on the role of the monarch in an independent Scotland.

The SNP supports keeping the monarchy but in slimmed-down form, subject to a referendum.

Alex Salmond: Will have questions

The SNP leader is also likely to raise the controversial question of land reform with the prince, who has a keen interest in environmental issues.

A party spokesman said today: "The prince's office has requested a private meeting and the SNP is happy to agree to that request.

"Clearly a number of issues will be raised, both by the prince and by Alex, and the SNP will be delighted to brief the prince on any aspect of SNP policy which he wishes to learn more about.