NICOLA Sturgeon has called on the Prime Minister to take “immediate steps” to crack down on secret tax haven firms operating in Scotland.

The First Minister wrote to Theresa May yesterday as it emerged UK ministers were promising to tighten up the law over the companies, known as Scottish limited partnerships (SLPs), which have been used to launder “dirty” money from criminals based overseas, in countries including Russia.

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The pledge follows pressure from the Scottish Government, SNP MPs and a three-year campaign of investigative journalism by The Herald, led by chief reporter David Leask.

It also comes just weeks after the nerve agent attack on former Russian double agent Sergei Skripal and his daughter Yulia in Salisbury.

At First Minister’s Questions yesterday Sturgeon welcomed the UK Government’s assurances, but demanded to know what specific moves were being undertaken following its inquiry into the issue.

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She said: “It is now more than a year since the UK Government’s call for evidence on this matter closed. Despite that, the UK Government has yet to outline specific proposals on how it plans to tighten the regulatory framework around SLPs. To reinforce how seriously we take the issue, I have today written to the Prime Minister, pressing her to take immediate steps to reform the law in this area.”

The First Minister praised the work of Leask in keeping the issue of SLP misuse in the public eye. She welcomed new regulations which came into force last June, but added more could be done to prevent “criminality being facilitated”.

“More needs to be done by the UK Government. This is a reserved area, and we will continue to press the UK Government to take concrete action to prevent the misuse of such partnerships,” she said.

“It is also appropriate to take this opportunity to acknowledge the persistence of Westminster colleagues on the issue and the efforts of David Leask at The Herald and others to keep it in the public eye.

“Nevertheless, I assure the member that, as I have done in my letter to the Prime Minister today, the Scottish Government will continue to put pressure on the UK Government to take action and to ensure that people cannot act criminally using Scottish limited partnerships as a shield for their criminal behaviour.”

Last weekend the SNP’s Westminster leader Ian Blackford called on the UK Government to “hit the Kremlin in the pocket” as he noted one SLP registered in Glasgow was used last year to transfer £160 million out of Russia.