The SNP will use its political sway to demand Labour starts HS2 in Scotland, not Birmingham, according to its deputy leader.

With the Scottish nationalists expected to secure the majority of seats north of the border, MP Stewart Hosie said they would use that power to try and shake-up plans for high-speed rail.

His comments will likely concern decision-makers in Greater Birmingham as HS2 is central to the region’s regeneration plans – for example, the Curzon Street Station is key to proposals to improve Birmingham city centre.

Mr Hosie, MP for Dundee East, said: “If the polls are right and our substantial lead is translated into votes in a hung parliament position, if there was a minority Labour administration which needed our help in order to get their legislation through, we might well make a case for saying look, let’s not have HS2 go to Manchester and Birmingham, let’s have it start in Edinburgh, Glasgow, coming through Newcastle as well, so we have a joined up high-speed rail network across the whole of the island, to the benefit of everybody, not just those travelling from Birmingham to the south.”

Rachel Maclean, Conservative parliamentary candidate for Birmingham Northfield, said the comments showed the SNP threatened a key regeneration scheme.

She said: “HS2 will play an essential part in ensuring the future prosperity of both this region and the wider UK – and Birmingham businesses are overwhelmingly behind it.

“The SNP have been explicit that that they will scrap HS2 as currently envisaged. A vote for any party other than the Conservatives risks putting Ed Miliband into Downing Street, propped up by the SNP, putting our economic security at serious threat.”

But Steve McCabe, Labour candidate for Selly Oak, told the Post it was an SNP fantasy.

He said: “We are not going to waste our time with the SNP’s fantasies. They also want to move Trident to Devonport and probably a golden elephant for everyone in Scotland.

“There is a good, strategic, case for HS2 to start in Birmingham. It is going to do a great deal for capacity and connectivity in Birmingham and also connect the cities to the north.

“If I had to spend my time dismissing every SNP fantasy, I’d be a very old man by the time we were finished.”