Danny Alexander has claimed that the SNP “lacks the will” to invest in north transport projects as he called for an upgrade of the main rail line to the Highlands.
The chief Treasury secretary claimed the Scottish Government had failed to deliver pledges to slash train journey times between Inverness and Edinburgh.
A spokesman for SNP Transport Minister Keith Brown countered by saying that the party was delivering improvements that the Liberal Democrats “ignored” while in office.
The clash marked the latest between the two parties as the battle for Mr Alexander’s Inverness, Nairn, Badenoch and Strathspey seat intensifies ahead of May’s election.
Mr Alexander said the SNP committed in 2007 to reduce rail journey times from Inverness to Edinburgh by 45 minutes but two-thirds of the line remains single track.
“The SNP’s dualling failure over the last eight years is not confined to the A9,” he said.
“Two-thirds of the Highland Mainline is still single track and no progress has been made to improve journey times to the central belt.
“What seems to be lacking is the political will of the SNP in Edinburgh who are more focused on central belt improvement than Highland infrastructure.”
Mr Brown’s spokesman responded: “No amount of shameless electioneering from Danny Alexander can disguise the fact that this SNP Government is delivering for Highland transport projects where the Lib Dems failed to.
“They failed to upgrade the Highland mainline during eight years in office at Holyrood – we are delivering a £5billion package of funding for our railways by 2019, including substantial improvements to the line between Aberdeen and Inverness.
“We are also pressing ahead with the dualling of the A9 and A96 – projects the Lib Dems ignored when they were in office.”