THE social media site Twitter is under renewed pressure to tighten up controls against online trolls as new figures emerged showing it had only pulled two abusive tweets in two years in response to official removal requests from the UK.

The details emerged as the social media site came under further criticism for failing to act over racist abuse of a Scottish Government minister which has remained in place for over two weeks despite demands for it to be removed.

Complaints were made to Twitter and the police about the abuse which targeted the Scottish Government's minister for Europe and external affairs Humza Yousaf.

Twitter figures reveal that in the two years since January 2012, Twitter received 57 Tweet removal requests from UK government, court, police or authorised reporters. Just two tweets were withheld.

Over the same period there were 311 requests for account information typically in connection with criminal investigations. Around 34% of requests result in "some information" being produced.

Jennifer Perry, chief executive of Digital Trust, which supports victims of all forms of digital abuse, warned that Twitter's failure to act was making unacceptable behaviour online acceptable and called for action.

She said: "If you allow racist or misogynistic comments it only normalises the behaviour, makes it more acceptable and it silences groups by intimidating them.

"Social media has to be more proactive and not allow these type of comments because it contributes to the current situation of intolerance whether racial, transgender or whatever."

Yousaf said: "Racism and other forms of online abuse can cause extreme distress to people who are victimised. It is unacceptable and should not happen in the first place, but unnecessary delays in taking action in response to such comments can only prolong such distressing situations.

"Twitter has a responsibility to take action as swiftly as possible when clear examples of abuse are reported to it. If it is failing to do so, then that needs to change as a matter of urgency."

Yousaf faced abuse after he published a message on Twitter on March 12 describing the BBC coverage of Jeremy Clarkson as "navel gazing".

A reply from Braydoe - @AcuraBray - replied: "Your a p***. Don't tell us white guys what we can and can't do."

The minister said he would be reporting the matter to the police, and copied in @policescotland into his comments.

Braydoe responded: "What a lad. Love a bit of police action!" He added: "Bloody hell I'm sh***ing myself. "

The matter was reported to Twitter by users.

One complainer said they had not received any response while the racist comments remain in full public view.

The @AcuraBray troll, who cites his location as London, had form for online abuse.

A tweet directed at Nigel Farage, leader of the UK Independence Party, also attacked Britons of Pakistani heritage, saying: "Do me and United Kingdom a favour sir. Get rid of p****!"

Continuing concern over the policing of Twitter was also highlighted after an SNP member who subjected Scottish Conservative leader Ruth Davidson to homophobic abuse was suspended from the party.

Davidson, an openly gay politician, was sent a tweet on March 18 posted under the Twitter profile Laird O'Callaghan, under the username @SparkyBhoyHH, which made obscene references to her sexuality.

Last month, Twitter's chief executive Dick Costolo said in an internal memo that the social media company should be embarrassed by the way it handles abuse.

"We suck at dealing with abuse and trolls on the platform and we've sucked at it for years," he said. "It's no secret and the rest of the world talks about it every day.

"We lose core user after core user by not addressing simple trolling issues that they face every day.

"I'm frankly ashamed of how poorly we've dealt with this issue during my tenure as CEO. It's absurd. There's no excuse for it. I take full responsibility for not being more aggressive on this front. It's nobody else's fault but mine, and it's embarrassing."

Asked about the racist tweet and its record on withholding tweets as a result of official requests, a Twitter spokesman said: "We do not comment on individual accounts, for privacy and security reasons."

He also added: "We review all reported content against our rules, which prohibit targeted abuse and direct, specific threats of violence against others.

"Users can report potential rules violations by following these steps. Additionally, our guidelines for law enforcement explain what private user information we have, and how authorities can request it. Our transparency report lists law enforcement 39 removal requests and 194 information requests from the UK in 2014."