Tories, Labour and the SNP on Sunday all flagged up potential sanctions and reforms designed to hit Vladimir Putin and his oligarch “cronies” in the pocket.

Russia is already feeling the effects of financial and trading penalties imposed by the US and European Union after it invaded and annexed Ukraine’s Crimean peninsula in 2014.

Now after the nerve agent attack in Salisbury all three main Westminster parties are gelling around new ways of stopping regime favourites - and perhaps the government itself - from laundering dirty money through property, banks or shell firms in the UK.

Government sources flagged up a series of targetted actions designed to make it easier to seize the unearned assets of Russians in Britain - and make it harder for connected Russians to enter the country to enjoy their wealth here.

Theresa May is expected to decide on the fine details of a response when she chairs the national security council on Tuesday.

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Labour, despite scepticism from its leader and over the evidence for the Salisbury poisonings, called for what it said would be a £1 billion “oligarch levy”.

Its wanted to tax property owned by offshore structures - not just those believed to be Russian - and crack down on Britain’s tax haven islands.

John McDonnell, the shadow chancellor, said: “If we want to really take the fight to the gangster politicians and Russian elites hiding their money in the UK, then we need serious measures like the ‘Oligarch Levy’, which will hit them where it hurts – in their wallets.

“It’s time to call an end to the use of our financial system and property market as a hiding place for rich foreign oligarchs and their money men by implementing measures like full transparency for tax havens and our levy on secret offshore property purchases.”

The party also backed a Magnitsky policy - based on 2012 US sanctions against Russian officials deemed responsible for the death of tax accountant Sergei Magnitsky.

The SNP Westminster leader Ian Blackford has long backed a Magnitsky scheme but on Sunday focused on calls for a crackdown on the abuse of shell firms, especially Scottish limited partnerships or SLPs.

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The Herald over the last three years has catalogued industrial scale abuse of such instruments, which can be owned anonymously through tax havens and serve the same purpose as Swiss bank accounts.

SLPs played a key role in the Russian Laundromat, the biggest laundering scheme every uncovered and widely believed to have been used by Kremlin insiders and associates.

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Ian Blackford

As part of an international team of investigative journalists, we have calculated at least £4 billion was funnelled through Scottish shell firms, including SLPs and limited companies.That is more than Scotch whisky exports.

Mr Blackford said: “One SLP registered in Glasgow was used last year to transfer £160 million out of Russia.

“Yet this is just scratching the surface given it is only one of thousands of SLPs set up over recent years, which need not register for UK tax or provide financial reports if conducting business abroad.”

Tory ministers were already concerned about SLPs before the Salisbury attack and have said they will announce reforms soon.

Some opposition politicians, led by the SNP’s Alison Thewliss, want all SLPs to have a UK-based real person to be accountable for their actions.

Labour’s Margaret Hodge wants to clean up SLPs too. Writing in he Guardian, she said:”All we need do is ask for a birth certificate or passport so we can assess the legitimacy of both the individual and their money.”