GLASGOW (AFP) - Voters in Glasgow said they hoped for a stronger voice for Scotland Thursday as Britain voted in elections set to see the Sottish National Party make big gains and become a potential kingmaker at Westminster.

Opinion polls during the campaign put the SNP on course to win most of the 59 House of Commons seats in Scotland, giving them a strong hand in the likely event that no party wins an overall majority.

"Whatever the outcome, whatever party wins, they are going to need to change how they see Scotland as a political entity," said John Lyons, a retired civil servant casting his ballot in Scotland's biggest city.

The Labour party, the official opposition party in the Commons, has long held sway in Scotland, winning 41 seats in the last general election in 2010. But it could lose most if not all of these to the nationalists - a stunning turn of events, just months after the SNP lost September's referendum on Scottish independence.

"My message is that we'll stand up for Scotland," said SNP leader Nicola Sturgeon, casting her vote in a Glasgow suburb.

Across Britain, the final opinion polls indicated the vote is too close to call, with Prime Minister David Cameron's Conservatives and Labour neck and neck.

If neither win a majority in the Commons, they may well have to turn to smaller parties to form a government - giving the SNP a strong hand.

"We will look to make alliances with people across the UK to make Westminster politics better," Ms Sturgeon said.