SCOTTISH Labour are facing a huge challenge in their traditional heartlands as new figures reveal a massive surge in SNP support in the west of Scotland.

While membership of the SNP had risen more than threefold from 25,652 to more than 80,000 by the end of last week, Glasgow had a near five-fold rise and Motherwell and Coatbridge had extraordinary six-fold increases.

In the fortnight after the referendum vote, SNP staff struggled to cope with the huge rise in membership applications. Only now is a picture emerging of where the surge is concentrated. What it shows will set off alarm bells in Labour as the increases are far greater in their areas of traditional support.

Scottish Labour leader Johann Lamont is already under pressure after Yes scored referendum successes in traditional Labour-supporting areas, especially in the west of Scotland.

The only four areas to vote Yes on September 18 were Glasgow, North Lanarkshire, West Dunbartonshire and Dundee.

SNP business convener Derek Mackay said: "Johann Lamont and the Labour Party's position in Scotland is growing increasingly precarious. The referendum unleashed a new spirit of democratic engagement and participation among the people of Scotland, and these people simply won't accept the same old politics as usual from Westminster."

As recently as 1998, Labour had almost 31,000 members in Scotland but 10 years later this had fallen to around 17,000 and the party stopped reporting figures. It is now believed to have dropped to below 13,000 and the SNP surge may well hasten that decline.

A Scottish Labour spokesman said: "We believe our aim of working in partnership to create a fairer, more equal country is a message for all of Scotland, not just traditional heartlands, as the SNP describe it. We don't presume support in any part of the country and we will work to win support for our vision all over Scotland."

But there was further evidence of a sense of dissatisfaction within Labour over the weekend with the announcement of a new internal pressure group.

It calls for the party to become more autonomous, perhaps under the historic name of the Independent Labour Party, campaigning for a "radical agenda for home rule in the 21st century" and pledging never again to work alongside the Tories.

Labour have dismissed the move, pointing out that one of those behind it, former spin-doctor Andrew McFadyen, was rejected in a bid to stand as a candidate.

Mr Mackay claimed the SNP's progress will further fuel alarm in Labour ranks. He said: "These figures are extremely encouraging, showing the SNP is enjoying a big rise in membership all over Scotland. To show such big increases in areas such as Glasgow and Lanarkshire is very gratifying.

"Scottish Labour made a mistake when they joined the Tory-led No campaign and repeated every scare story and every bit of Tory negativity during the campaign."

He added: "With this growth in membership, the SNP are in an extremely strong position to hold the Westminster parties to account on their vow of substantially more powers for Scotland - as by far the third biggest party in the UK, and with more and more support in traditional Labour heartlands."

But the more than trebling of SNP members could bring tension and in-fighting during candidate selection for the next Holyrood election with the more conservative wing fearing that a wave of largely left-wing incomers could see sitting MSPs and even ministers fighting for their survival.

Meanwhile. the Scottish Greens also saw a three-fold upsurge in membership in recent weeks, taking it to 6300 card-carriers, creating a party which co-convener Patrick Harvie described as full of "new energy, enthusiasm and talent".

At their party conference at the weekend, which had to be moved to a bigger venue, he told delegates: "It's hard to overstate how much of a moment this is."