KEIR Starmer has been urged to “stop blocking” the Scottish Parliament from gaining control over employment law.

Labour have been accused of wanting to keep powers over workers’ rights and trade unions in Westminster’s hands in an International Workers’ Day challenge from the SNP.

Mhairi Black, the party’s deputy leader in Westminster, said Scottish independence was the “only way to guarantee workers' rights are protected” after an anticipated constitutional review penned by Gordon Brown failed to call for employment law to be devolved to Scotland.

The SNP have previously argued giving Holyrood the powers to make its own legislation on workers’ rights could see an end to controversial “fire and rehire” tactics as well as a reversal of draconian restrictions on trade unions.

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Black said: “As millions of people mark International Workers' Day, it's never been more important that Scotland gets full control over employment law - so we can advance protections for workers and defend Scottish families from creeping Tory attacks on workers' rights.

"Independence is the only way to guarantee workers' rights are protected in Scotland. That's clearer than ever, as the Tory government attacks the right to strike and waters down the protections we all rely on.

"But for as long as Scotland remains under Westminster control, it's essential full powers over employment law are devolved to Scotland without further delay.

"Keir Starmer must stop blocking the devolution of employment law – or his pro-Brexit Labour Party will become even more indistinguishable from the Tories.

"At the general election next year, voting SNP is the best way to beat the Tories in Scotland. The SNP is the only party offering a real alternative - and a strong team of SNP MPs will hold Westminster to account and get the best deal for Scotland."

The SNP have repeatedly accused Labour of blocking the devolution of employment law to the Scottish Parliament during the time of the post-No vote Smith Commission, designed to decide which new powers to give to Holyrood.

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The party have defended this move by saying they were acting on the advice of the Trades Union Congress (TUC), which took the opposite view from its sister organisation the Scottish Trades Union Congress.

In a debate in September last year on the topic, Labour’s only Scottish MP Ian Murray claimed his party wanted to devolve employment law – and hinted Brown’s review would make that recommendation.

Challenged by SNP MP David Linden on whether the next Labour manifesto would include a promise on devolving employment law, Murray said: “It will have a clear commitment to implement what we are currently doing in terms of the Labour Party’s commission.

“I am not going to discuss what is in the commission in a Westminster Hall debate because it is being finalised and will be launched in the early part of November. However, [Linden] will not be disappointed with some of the outcomes of that detailed work.”

Labour were approached for comment.