It came just days after Scottish leader Kezia Dugdale joined the chorus of calls for the left-winger to go, insisting she could not lead the party in Scotland without the support of her MSPs.
Mr Corbyn has suffered a mass exodus of frontbenchers and lost a vote of confidence by 172 votes to 40 among his MPs this week. A leadership contest is now expected with former shadow business secretary Angela Eagle poised to stand.
But a letter today signed by three senior Labour MSPs in Scotland says the behaviour of agitators will “break the hearts” of party members.
Neil Findlay, who led Mr Corbyn’s leadership campaign in Scotland last year, as well as former union organiser Richard Leonard and Mr Rowley have signed an open letter backing the leader.
It states: “Jeremy Corbyn was democratically elected as leader of the Labour Party with almost 60 per cent of members supporting him. His campaign succeeded because he offered an alternative to the austerity driven divisions within our economy and society. The events of the last few days have broken the hearts of Labour Party members across the UK.
“Labour Party members are not passive onlookers to be used and exploited at election time, only to be ignored thereafter – they are the lifeblood of our party, we are nothing without them. Democracy wherever it is found is a precious thing – we therefore want to make it clear that we wish to uphold the democratic rights of Labour Party members and support the democratically elected leader of the Labour Party, Jeremy Corbyn.”
Ms Dugdale had called on Mr Corbyn to consider his position in a statement earlier this week.
“I would not be able to do my job if I did not have the support of the parliamentary party, regardless of the mandate that members give me. Jeremy should reflect on the outcome of the PLP vote but I would not carry on in similar circumstances,” she said.
Mr Rowley had been critical of the decision of Edinburgh South MP Ian Murray to resign as shadow Scottish secretary as he called on Mr Corbyn to stand down as leader.
The civil war within the party spilled over into Scotland earlier this week when more than 200 Scottish Labour politicians and members signed an open letter calling for Jeremy Corbyn to stand down as UK party leader.
Signatories include Daniel Johnson, MSP for Edinburgh Southern, and Catherine Stihler MEP as well as former MP and shadow Scottish secretary Margaret Curran.
An earlier open letter to Mr Murray from 80 Scottish Labour figures, including Elaine Smith MSP, condemning him for handing a “gift” to the SNP and Tories and supporting Scottish Labour deputy leader Alex Rowley for criticising the MP for Edinburgh South.
Signatories included Scottish Labour councillors, the executive committee of Scottish Young Labour and members of Mr Murray’s own constituency Labour party.
It came as a senior Scottish Labour MEP yesterday refused to rule out backing an independent Scotland if it becomes the best option for securing the country’s links with Europe after the Brexit vote.
David Martin, who is the UK’s longest-serving MEP, said that the result of last week’s referendum had left Scotland in a “sub-optimal position”.
While the UK as a whole voted to leave the European Union, 62 per cent of Scots voted to stay, a result which prompted First Minister Nicola Sturgeon to say another independence referendum is “highly likely”. Mr Martin, a Labour MEP since 1984, stressed that independence “is not my position”, but added that at the moment it was impossible to judge what the best arrangements for Scotland would be.
When asked about Scotland’s relationship with the EU, he said “the consequence of last Thursday’s vote is we are in new territory” and that things “will be different”.
Asked if he could back independence for Scotland, Mr Martin said: “That’s a decision that could not be made at the present time, until we know the conditions for the UK exit it’s impossible to judge whether Scotland within the United Kingdom is best placed or otherwise.
But he added: “I’m certainly not ruling it out.”