RUTH Davidson has been urged to apologise after mocking the accent of an SNP MSP, amid claims the language of the second referendum debate is already “divisive” and “disgusting”.

The Scottish Conservative leader was accused of resorting to “hectoring and pathetic personal jibes” after joking about the nasal twang of South of Scotland MSP Joan McAlpine.

As the debate on referendum powers resumed after last week’s suspension because of the Westminster terror attack, Nicola Sturgeon opened with a plea for tolerance, saying: “Let us start today as we mean to go on - positively, passionately and respectfully."

Green Andy Wightman added: “Whatever transpires during the coming years, as politicians we are responsible for setting the tone of public discourse, so I am committed to engaging in debate and discussion with respect, tolerance and empathy.”

The SNP's Kate Forbes was widely praised for her contribution, which included a verse of Gaelic poetry, but other MSPs were attacked for lowering the tone, as the quality of the debate veered erratically from dignified to disorderly.

In her opening remarks, Ms Davidson was jeered for quoting Ms McAlpine’s words and then adding: “I won’t do the accent”.

Ms Davidson also told Ms Sturgeon abruptly to “sit down” when the First Minister tried to intervene a second time in her speech.

Interventions are traditionally handled with a polite refusal.

Transport Minister Humza Yousaf tweeted: “Worst I've heard Ruth Davidson in chamber - mask slips as she resorts to personal attacks & rudeness towards opponents”, while the SNP’s James Dornan added: “Ruth Davidson clearly thinks 'now is not the time' for respect.”

But Ms Davidson also accused the SNP of bad behaviour, raising the outburst by Environment Secretary Roseanna Cunningham last Wednesday when the debate was suspended.

Tory sources said Ms Cunningham, who was filmed gesticulating at Tory MSPs, said “this is because you didn’t want to talk about independence”, although the SNP deny this.

Ms Davidson said: “In what was a disgraceful episode, we were shouted at by SNP members and told that we were frightened to debate independence.

“We are not, but we are sick of it, and most people in Scotland have had enough, too.”

Scottish Labour whip James Kelly said the 2014 referendum was not “a celebration of democracy" but sour and antagonistic because Yes supporters tried to frighten opponents.

He said there had been “pensioners scared to vote No because of the aggressive and intimidatory nature of the Yes campaign”.

He said: "For those who were chased up and down streets, being threatened and intimidated, it was not a celebration of democracy. That is why people do not want to return to a divisive second independence referendum."

SNP MSP Sandra White criticised the remarks, adding: "The language that has been used to me by the unionist opposition parties is unbecoming of the Parliament.

"They have set a terrible example to our young people, to the Scottish people and to the international world. Their language has been disgusting."

Nationalist Clare Haughey added: "I have been so disappointed by the language that some members have used during this debate. Language has been weaponised, with members using words such as battle, fight and divisive. I have heard accusations of arrogance, slurs and - yes - even rabid nationalism."

Tom Arthur of the SNP added: "Those who oppose independence, particularly in public life, have an equal responsibility to resist cynically employing inflammatory language for political gain."

Tory Murdo Fraser criticised Ms Sturgeon of failing to discipline Dave Doogan, deputy leader of SNP-run Perth & Kinross Council, who last month said Scotland had been “under the heel of foreign influence and power for 300 years”, with "Redcoats" trying to extinguish smaller cultures "on an island of coffins”.

Mr Fraser said Mr Doogan’s council candidacy has since been endorsed by John Swinney

“The use of language divisive in her own party is rewarded with an endorsement from her deputy. She needs to start leading by example.”

Mr Swinney said he and other politicians were routinely subject to “hostile and aggressive” comments on social media, but needed to “lead by example” to raise the debate.

Ms Haughey said later: “This display by the Tory leader was obnoxious and deeply unpleasant – a politician with any class would offer a full apology.”