Nicola Sturgeon has insisted she will not cry "crocodile tears" over Labour's "pitiful and sad" demise.
The Scottish First Minister told Alastair Campbell, who was director of communications for Tony Blair, that Labour was not "capable" of providing strong opposition to the Conservative government and Westminster, and it was her SNP that was "filling that void".
Campbell interviewed the SNP leader for the latest issue of GQ magazine in the period between Labour's defeat at the general election and the election of new leader Jeremy Corbyn.
The left-winger succeeds Ed Miliband, who stood down after the Tories unexpectedly won a majority at Westminster, with Labour losing all but one of its MPs from north of the border.
He asked Ms Sturgeon about the state of the Labour Party as she had played a "role in its demise".
The First Minister and SNP leader told him: "I'm not going to cry crocodile tears. The SNP and Labour have long been opponents, but there is something pitiful and sad about it.
"The UK needs a strong opposition and Labour shows no signs of being capable of being that.
"The SNP is filling that void and will go on seeking to do that. As First Minister, I think every country, every democracy, benefits from a strong opposition."
She continued: "I feel sorry for generations of Labour voters and supporters who must look and wonder what on earth has gone wrong and what Labour is for.
"In Scotland, it is not rocket science. Labour got lazy, complacent, arrogant and lost any real sense of purpose.
"The question 'What is Labour for?' does not have an easy answer in Scotland, or in the UK. What is saddest is the failure to stand up and argue your view of the world."
She also told Campbell - who has spoken publicly about his drink problem - that Scotland has an "unhealthy" relationship with alcohol.
While she said this was "improving", she added: "What is most unhealthy is this identification we have, not unique to Scotland but certainly the case here, where we identify having a good time with drinking alcohol, having a sh*t time with drinking alcohol, being happy with drinking alcohol, being sad with drinking alcohol.
"It is too much of an ever-present, regardless of our mood."
In a bid to tackle the relationship between the price of alcohol and the amount drank, the Scottish Government has legislated for the introduction of a minimum unit price, but its introduction has been delayed by a legal challenge.
The full interview can be read in the November edition of GQ, which goes on sale on Thursday October 8.