IAN Blackford has threatened to sue a Tory MP over a "false and defamatory" jibe about the SNP chief being an arms dealer.

Over the weekend, a report in the Mail on Sunday claimed the investment fund chaired by Blackford profited from defence deals, and had made money off the back of weapons used in the war in Yemen. 

According to the paper, Golden Charter Trust indirectly benefits from arms manufacturers including BAE Systems, Raytheon, Airbus, Northrop Grumman and Harris Corporation.

All of those firms have ties to Saudi defence.

Thomson tweeted a picture of the article with the line: “Just a simple arms dealer."

He deleted the tweet about two hours later.

The MP was referencing a remark Blackford made in the Commons during last year's budget debate when he said he was “just a simple crofter with ten acres”.

According to the Times, solicitors acting on behalf of Blackford have now written to Thomson asking him to say sorry. 

A senior SNP source told the paper: “His false and defamatory statement will require an apology and a charitable donation.”

A source close to Thomson said: “Ross has received the letter and will respond in due course.”

According to Blackford’s register of interests, despite working just 32 hours a year, he earns a whopping £3091 a month from the trust.

The Ross, Skye and Lochaber MP, a former investment banker before entering Parliament, has long been a critic of the UK government’s unwillingness to prevent British arms sales to Saudi Arabia.

At Prime Minister’s Questions last October, he told Theresa May that “Saudi Arabia's regime is responsible for multiple human rights violations” and that “critics face death by crucifixion, teenagers tortured and women imprisoned for campaigning for their human rights.”

He called on May to show “moral leadership” and no longer approve new arms exports to the Saudi kingdom.

The Scottish Tories accused him of "rank hypocrisy." 

A spokesman said: “Do what I say not what I do is the hallmark of the SNP and Mr Blackford is no exception. People in Scotland have had enough of the Nationalists' rank hypocrisy.”

Labour’s Lesley Laird called for Blackford to divest or resign his chairmanship of Golden Charter.

“It is staggering that Ian Blackford has been privately profiting from arms sales to Saudi Arabia at the same time as publicly condemning them and just another example of the SNP saying one thing and doing the other.

“Ian Blackford should either divest from these companies or, better still, resign his chairmanship of Golden Charter and provide his constituents in Ross, Skye and Lochaber with a full-time MP,” added the Shadow Scottish Secretary.

Speaking on the BBC’s Sunday Politics Scotland, Blackford said: “It’s all stuff and nonsense, is anybody really saying that people shouldn’t invest in British aerospace which is a company that makes equipment for the UK defence industry, of course that’s just nonsense.

“Secondly, of course, the SNP is very clear that the government should take action to make sure that we’re not selling arms to Saudi Arabia,."