The SNP has warned Scottish Labour not to interfere in the race to succeed Nicola Sturgeon.
Jackie Baillie said earlier this week that "murky internal politics" could not be allowed to derail the process to find the next First Minister.
The Labour health spokeswoman wrote to senior Nationalists to claim their party had a "long track record of secrecy and cover-up" which raised questions about their "ability to conduct this race fairly and honestly".
But Michael Russell, the SNP president, has today hit back at Baillie and accused her of "grandstanding".
It comes as the Nationalists deal with the fall-out from a stormy leadership contest that has already seen splits open up in the party.
In his letter, Russell said: "I would first of all want to welcome your implicit support for the democratic process, which is particularly notable given your previous refusal to accept that universal norm with regard to the clear mandate gained by the SNP in successive elections for the holding of an independence referendum.
He added: "I must however refute your totally false assertions regarding the SNP and its processes. In fact the party has for many years ensured that members are well served by arranging independently run and verified internal elections and, when contested, candidate selections as well.
"The same company has been contracted for a decade or more to run these elections and does so to the highest standards."
The letter concluded: "I can assure you that as a party we are fully aware of our heavy responsibilities at this time, given that the person elected will not only be our leader, but will also be our nominee for the post of First Minister.
"Consequently we will firmly resist any and all interference in these matters including rejecting every attempt at publicity seeking grandstanding, such as is contained in your letter."
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