The SNP now has a "record" 20,000 members, the party has claimed.

Deputy leader and Deputy First Minister Nicola Sturgeon said the party was now the largest in Scotland.

The Nationalists added that with 20,139 members, the number of people in the party was now more than double the total eight years ago, when it was 9,450.

They said almost 4,000 new members had signed up over the course of 2011.

Ms Sturgeon said: "Our 20,000-membership milestone is the icing on the Christmas cake for the SNP."

She added that the party's record membership came after a "momentous year for Scottish politics and for the SNP", with the Nationalists securing an historic overall majority at Holyrood in May's election.

She continued: "With 20,000 members all working to make Scotland better, the SNP is now the largest party in Scotland and is increasingly the natural choice of those wanting to build a better Scotland.

"We are winning new members and public support as voters recognise the successes of the SNP in Government and our commitment to make Scotland smarter, fairer and wealthier."

SNP business convener Derek MacKay said: "In May this year over 900,000 people across Scotland voted for the SNP and since then we have seen membership continue to build, making the SNP Scotland's largest political party."

He went on: "The SNP now has a record 20,000 party members. That is an astonishing increase of nearly 4,000 members in one year and a sign of the phenomenal support the people of Scotland have given the SNP this year.

"We are on course to meet the target set this October of doubling party membership in the run-up to the referendum on Scotland's independence."

SNP leaders have already pledged to hold a referendum on independence in the second half of Holyrood's five-year parliamentary term, but no date for this has yet been revealed, despite repeated demands from opposition politicians for the Scottish government to name the date for the poll.