THE SNP's income last year almost trebled thanks to individual donations and a sizeable bequest, while the Conservatives saw their UK-wide revenue drop by almost £20 million to its lowest level since 2003.

Official figures from the Electoral Commission showed that in 2011, the year of the Scottish parliamentary elections when the Nationalists won their landslide victory, the SNP brought in £5 million and spent £3.5m.

This compares to the previous General Election year when the respective figures were £1.9m and £2.2m.

The parties' accounts for 2011 published by the commission showed the Conservatives took in £23.7m and spent £22.8m with liabilities totalling £8.7m.

Labour also saw income fall from £36.3m to £31.3m with its post-election slump tempered by defeat making it eligible for so-called "Short Money" taxpayer support.

Despite losing state support, the Liberal Democrats drew in £6.2m, down from the previous year's £9.6m.

The latest accounts also showed the LibDems suffered a 25% drop in UK party membership in just one year; from 65,038 in 2010 to 48,934 members at the end of 2011.

The SNP seized on the numbers pointing out how the fall contrasted with a 24% increase in its membership during the same period and there had been a further 16% rise to 23,376 members by June 30.