THE present first-past-the-post election system would be scrapped and the electorate would vote for MPs in order of preference under SNP plans for a shake-up of Westminster elections.

Nicola Sturgeon will commit to replace the UK's present voting system with the Single Transferable Vote (STV), which is used for Scotland's councils.

Sturgeon will set out plans for "Making Westminster more democratic" when she unveils the SNP election manifesto on Tuesday.

The party has already said it will launch proposals in the Commons to give 16 and 17 year olds a vote in UK General Elections – a move that would bring it into line with Holyrood.

However, the SNP said it would also back any moves at Westminster to replace first-past-the-post system with STV, a form of proportional representation.

The SNP manifesto will say: "We will vote for the replacement of the first-past-the-post system with proportional representation. The SNP supports the Single Transferable Vote, a system that makes sure every vote and every part of the country counts."

Sturgeon will also call for more to be be done to help register the millions of people missing from the electoral register

Meanwhile, a leading SNP figure attacked controversial Tory plans to force people to show photo identification when they vote as an "utter disgrace". Under Tory manifesto plans people failing to produce a passport or driving licence would be refused ballot papers at polling stations.

However, Mhairi Black, the SNP's candidate in Paisley and Renfrewshire South, said that introducing compulsory photo-ID at elections would restrict people's democratic rights.

She said: “The Tories want to limit who gets a say, and who plays a part in UK politics. They’re content for young people and those who are less well off to be disenfranchised — to be told what’s best for them rather than getting to choose for themselves.

“The gap between those eligible to vote and those on the electoral register has never been wider. That is an utter disgrace and the Tories plan to make things even worse — with compulsory ID at polling stations yet another hoop for people to jump through just to exercise their democratic right.

“16 year olds who get to vote in Scottish elections don’t have a driving licence. It’s the best part of £100 for a new passport. In essence, the Tories want young people to pay to take part in democracy."