The Scottish National Party has published its blueprint for a written constitution for an independent Scotland.

On Monday SNP vice-president professor Neil MacCormick set out a "constitution for a free Scotland".

His move comes as the nationalists step up preparations for next year's elections to the Scottish parliament.

A constitution, the SNP believes, will be a key factor in persuading Scots of the benefits to be had from backing an independent Scotland in a referendum.

It set out the rights of citizens and defined the powers and responsibilities of government and parliament.

Six key areas highlighted by the party are:

• The absolute right of the people of Scotland to self-determination and to sovereignty over the territory and natural resources of Scotland.

• The constitutional entrenchment of the fundamental rights and liberties of the people of Scotland, without discrimination on any grounds such as sex, race, colour, religion, personal beliefs, ability, age, status or sexual orientation.

• A prime minister elected by parliament, and a ministerial team confirmed by election in parliament.

• An inclusive definition of citizenship, and voting rights based on residence not ethnicity.

• A single-chamber parliament, elected by proportional representation.

• Independence of the judiciary, with appointments made by an independent Commission on Judicial Appointments, free from government interference.

The constitution would come into force following the Scotland's transition to independence.

Professor MacCormick said the proposed constitution would guarantee "the sovereignty of the Scottish people, their freedom and liberties".

"It forms the basic framework for a new independent Scotland and will be presented to the people in advance of a referendum on independence.

It sets out the rights of citizens of an independent Scotland, and defines the powers and responsibilities of government and parliament."