Political optimism has been tempered by allegations of polling station intimidation in Scotland.

Scottish Conservative leader Ruth Davidson took to Twitter with allegations of voter intimidation in Dumfriesshire, Clydesdale and Tweeddale, where Scotland's only Tory MP David Mundell is hoping for a return to Westminster.

She said: "Disturbing reports of people being turned away from an Annan polling station by burly blokes if they say they don't support a certain party."

Police Scotland and Dumfries & Galloway Council said they are currently looking into the allegations, although The Independent understands that there isn't anything in the claims.

General election 2015: Polling day Show all 16 1 /16 General election 2015: Polling day General election 2015: Polling day General election 2015 Nuns arrive to vote at a polling station at St John's Church in Paddington, London General election 2015: Polling day General election 2015 A voter leaves the White Horse Inn in Priors Dean, also known as the 'Pub with no name', which is part of the East Hampshire constituency and acts as a local polling station on the day of the election General election 2015: Polling day General election 2015 General view of inside the White Horse Inn in Priors Dean General election 2015: Polling day General election 2015 People cast their votes as a man uses a punch bag in the East Hull Boxing Academy, which is being used as a polling station in Hull General election 2015: Polling day General election 2015 Penny Higbee waits to greet voters at her home in Routh, East Yorkshire, which is being used as a rural polling station General election 2015: Polling day General election 2015 Voters in Ironbridge, Shropshire, arrive to cast their vote at The Iron Bridge Tollhouse General election 2015: Polling day General election 2015 A voter arrives at the North West Ambulance Service Station at Milton Green, Cheshire, which is being used as a polling station as Britain goes to the ballot box General election 2015: Polling day General election 2015 A polling station has been installed in a launderette in Oxford General election 2015: Polling day General election 2015 SNP candidate for the Gordon constituency and Former First Minister Alex Salmond with first time voter Nicki Falconer, and her family, (L-R) Mackenzie, Nicki, Skye, Alex Salmond and Keiran at their local polling station in the Gordon constituency in Ellon, Scotland General election 2015: Polling day General election 2015 Prime Minister David Cameron and wife Samantha after casting their votes at Spelsbury Memorial Hall, Witney General election 2015: Polling day General election 2015 Liberal Democrat leader and Deputy Prime Minister Nick Clegg and his wife Miriam Gonzalez Durantez arrive at Hall Park Hill Community Centre to cast their votes, in Sheffield General election 2015: Polling day General election 2015 Labour Party leader Ed Miliband and his wife Justine Thornton leave the polling station at Sutton Village Hall in Sutton after casting their votes in the 2015 general election in Doncaster General election 2015: Polling day General election 2015 First Minister of Scotland and leader of the SNP Nicola Sturgeon, votes with her husband Peter Murrell in Glasgow, Scotland General election 2015: Polling day General election 2015 Ukip leader Nigel Farage arrives to cast his vote for the South Thanet constituency in Ramsgate General election 2015: Polling day General election 2015 Plaid Cymru leader Leanne Wood arrives at a polling station in Penygraig, Rhondda, Wales General election 2015: Polling day General election 2015 Green Party leader Natalie Bennett after casting her vote at Ossulston Tenants' Hall, London

Elsewhere, SNP heavyweight Alex Salmond insisted his party's "tails are up across the country" as he cast his vote in Ellon, in the Gordon constituency where he is standing.

Mr Salmond joined SNP voter Nicki Falconer, who voted for the first time in last year's independence referendum and has since joined the party.

SNP leader Nicola Sturgeon said Scotland's political future is now "in the hands of the voters" after voting early at Broomhouse community hall in Glasgow accompanied by husband and SNP chief executive Peter Murrell.

Scottish Labour leader Jim Murphy said "the sun is shining and there is a huge amount of energy and confidence" in the party as he voted at Busby Primary School in the East Renfrewshire constituency he has represented since 1997.

"I've always been the underdog in this constituency," he said.

"It's usually the Tories who are favourites but the bookies say this time round it's the SNP, but I always enjoy confounding the pollsters, the pundits and the bookies. We've had a great response."

Former Labour shadow foreign secretary Douglas Alexander said "a Labour government is within touching distance" as the polls opened in Paisley and Renfrewshire South while his SNP opponent Mhairi Black urged people to "vote for a fresh start".

Liberal Democrat Equalities Minister Jo Swinson said it had been "a glorious start to polling day" in East Dunbartonshire.

Scottish Green MSP Alison Johnstone joined Edinburgh South Green candidate Phyl meyer at Marchmont St Giles polling station.