SCOTLAND'S Tory MPs have been dubbed the 'Useless 13' for failing to speak out against a “power grab” by Theresa May over her Brexit plans to repatriate powers from Brussels to London.

The SNP's Westminster leader Ian Blackford attacked the Scottish Tory MPs for their silence since the General Election on May 8.

He challenged Scottish Tory MPs to use their position as one of the most powerful Scottish blocs at Westminster in decades to oppose the wholesale transfer of powers from Brussels to London.

Speaking to the Sunday Herald, Blackford labelled the performance of the 13 as "useless" since the election, when May's government lost its overall Commons majority.

Blackford challenged Scottish Tory MPs to deliver on Ruth Davidson’s election pledge for the party to “forcefully” speak up for Scotland at Westminster.

His call came after Nicola Sturgeon said a "blatant power grab" by the Tories poses the biggest threat to the Scottish Parliament's powers since the vote for devolution two decades ago.

Writing in last week's Sunday Herald, Sturgeon said the devolution settlement is under unprecedented attack from the UK Government's Brexit plans.

Blackford said Scottish Tories have to decide which side they are on as London prepares to take charge of policy areas traditionally devolved to Holyrood such as farming and fishing.

Last night, he accused Scottish Tory leader Ruth Davidson and Scottish Secretary David Mundell of failing to use their influence with May's Government over the issue.

Blackford said: "Despite Ruth Davidson's pledge for her MPs to speak up for Scotland at Westminster, her 13 Tory MPs have failed spectacularly by supporting the UK Government's flawed EU Withdrawal Bill and a power grab from the Scottish Parliament.

"The useless Scottish Tory MPs have failed to use their position to oppose the transfer of powers from Brussels to Westminster – ignoring the principles of devolution.

"Despite David Mundell promising a 'powers bonanza', the Tories are unable to name a single power that will come to Holyrood. Ruth Davidson is often fond of boasting that she will not just do whatever her Westminster bosses tell her to do – but the reality is on issue after issue, she does exactly that.

“The Scottish Conservative leader admitted that her biggest fear is the potential economic hit with Brexit, and that we won’t 'bounce back'. Yet her new Tory MPs failed to stand up against Theresa May’s plans for a hard Brexit and do all they can to help keep us in the Single Market."

Davidson, speaking the weekend after the election, said: "I'm going to make sure that along with the 13 MPs we're sending to Westminster, we put Scotland's case forcefully and make sure that we deliver for Scotland and make sure that the Union delivers for Scotland too."

Former Labour First Minister Henry McLeish claimed the Westminster "power grab" was an abuse of Scotland's democratic rights.

McLeish, who presided over the introduction of devolution legislation as a Scotland Office minister at Westminster in the late 1990s, said: "Scotland's parliament is being simply ignored by the tyranny of Theresa May's government at Westminster. The 13 Scottish Tory MPs are no longer Ruth's 13, they are Theresa May's 13.

"Having success in the General Election in Scotland doesn't allow them to slip away at Westminster and not tell Scots what they have to say on key issues."

In response, Scottish Conservative MP John Lamont said: “This is yet more misleading nonsense from the SNP. It’s time the SNP started working in the interests of Scottish people by working with the UK Government to get the best possible deal for Scotland and the UK as we leave the EU.”