PRESSURE is mounting to bring executives from Twitter and Facebook before the Scottish Parliament to account for the catalogue of death threats, rape threats, abuse and intimidation on social media.

It follows revelations in the Sunday Herald last week that Nicola Sturgeon and opposition leaders in Scotland have suffered a horrific catalogue of threats and violent online abuse.

Scottish justice secretary Michael Matheson told the Sunday Herald that the social media giants "have a moral responsibility" to protect the public from online abuse and help police catch the aggressive trolls responsible.

He said UK executives from the companies had to "show leadership" as pressure grows on them to appear at Holyrood.

Last night, Matheson branded the abuse a "hate crime" and challenged the American-based social media providers to get to grips with the issue.

Holyrood justice committee member Mary Fee said social media firms should now be summoned to Holyrood.

She warned that social media "has dark corners where misogyny, racism and hatred live and it is right that a light is shone on these areas and action is taken".

The Labour MSP added: “All social media sites must face up to greater accountability for what takes place on their platforms.

"Twitter, Facebook and Google must be willing to come in front of the Scottish Parliament and explain what action they are taking to find and stop abusive accounts.

“We need to see greater co-operation between these sites and Police Scotland to ensure that appropriate action is taken and that we make clear that such abuse is simply unacceptable online.”

Green MSP, Alison Johnstone, echoed the call. She said: “As we continue to head towards an independence referendum it’s essential we keep the online debate as cordial as possible.

"There is also a role for the social media platforms to explain what they can do to curb abuse, while ensuring free speech is not restricted.”

Holyrood's justice committee convenor Margaret Mitchell, a Tory MSP, said: "Online abuse has got to the stage where the big providers have to be held to account. There must be a way of policing the more extreme posts whether it's against politicians or any individual.

"There should be a look at investing in the infrastructure to improve protection as it's become so corrosive for society in terms of mental health and suicide.

"It really needs not just a national solution, not just from one parliament - it's got to be for global organisations to look at, like the UN."

Legislation to regulate the internet remains reserved to Westminster. Both Twitter and Facebook have so far refused to say whether they would appear before MSPs.

Speaking to the Sunday Herald, Matheson said: “There is no excuse for any form of hate crime. It is completely unacceptable for anyone to peddle hatred, abuse or bigotry on-line. There is no such thing as a victimless crime and those who indulge in such cowardly behaviour should be held to account.

“While the legislation in this area is reserved, we support the work of our law enforcement agencies to tackle this issue."

He added: “As we seek to maximise the undoubted benefits of technological advances and greater connectivity, it is essential that all social media companies and ISPs take responsibility and show leadership by constantly reviewing their procedures to tackle unlawful and unacceptable communications.

"They have a moral responsibility to ensure that the people using their services are not needlessly exposed to abuse and continue supporting our law enforcement agencies to pursue those who fail to get the message.”

As the Sunday Herald revealed last week, Police Scotland is investigating a torrent of online abuse against Sturgeon, including death threats, threats of violence and extremely offensive and sexualised insults.

Police yesterday confirmed investigations were still under way into the abuse highlighted. Scottish Labour leader Kezia Dugdale and Scottish Conservative leader Ruth Davidson have also been on the receiving end of online attacks from trolls.

A Twitter spokesperson would not say whether the company's executives would appear before MSPs, but stated it had made a "host of new safety changes" in recent weeks. Facebook declined to comment on the calls for it to appear.