IAN Blackford has written to the Prime Minister over the conduct of a Tory MP who shouted "suicide" as he was speaking.

On Tuesday, Ian Liddell-Grainger infuriated the SNP when he shouted “suicide” as Blackford asked what options were open to Scottish parliamentarians, in the aftermath of the EU Withdrawal Bill debate.

READ MORE: Tory MP defends 'suicide' remark and calls SNP 'wankers'

The SNP Westminster leader raised the issue in a Point of Order in the chamber.

Speaker John Bercow responded: "I have just been advised by a Government whip that the member concerned, who is not present at the moment, maintains that he was referring to political suicide.

"However, I would just say I do think this underlines the importance of us using language with great care."

Blackford has now written to Theresa May over her MP's behaviour.

He said: “To shout 'suicide' across the chamber is not fitting of a Member of Parliament and it should not be tolerated.

“Earlier this week I asked what options are available to us in Parliament to ensure that the Government understands the real concern among people in Scotland at the unprecedented power grab and how can we could make sure that our voices are heard. For Mr Liddell-Grainger to shout 'suicide' is reprehensible.

“Suicide is a serious matter, with almost 6000 people taking their own lives across the UK a year.

“I understand when I raised this matter previously Mr Speaker had not heard the comment. However, the comment is heard very clearly on the video of the sitting that I took the trouble to watch.

“A few months ago, I met with the Prime Minister and other party leaders to discuss how we can combat bullying behavior in the House of Commons. It was agreed that we should find a solution.

“This is not the first time our MPs have suffered abuse in the Chamber. Tory MP Sir Nicholas Soames was forced to apologise to Tasmina Ahmed-Sheikh during a statement by the Foreign Secretary, for making ‘woofing’ noises at her.

"This sort of behaviour is unacceptable – MPs must lead by example. I have suggested to the Prime Minister that she raises this issue with the house next week."

Liddell-Grainger has said he was referring to "political suicide", and that he is sensitive to mental health issues as a former soldier.

He also said the SNP were "a petty bunch of wankers who have ruined [Scotland]".