The rise of 22,104 new members (as of 9.45am on Tuesday morning) makes the SNP the UK’s third biggest party: the last confirmed UK-wide Lib Dems’ membership number was 43,451 at the start of this year while Ukip had 38,124 members on 19 May.
Since the referendum, an additional 3,000 people have also signed up to join Scotland’s Green party.
The figures were released by the SNP ahead of a speech by Alex Salmond, the party’s current leader and first minister of Scotland, at the opening of the Scottish parliament later on Tuesday. He is expected to call for the voting age to be lowered to 16 ahead of the general election, after the enthusiam shown for voting in the referendum among this younger age group.
The SNP said that the surge in membership put the Westminster establishment under “serious pressure to deliver” on the new powers for Scotland which the No camp promised during the campaign.
SNP business convener Derek Mackay said on Monday that the referendum was a “triumph of democracy” and added: “the new wave of democratic engagement and activism the Yes campaign inspired shows no signs of stopping”.