Penny Mordaunt has hit out at the SNP in a furious Commons rant, describing the party as "self-obsessed, self-pitying and self-delusional".
In a brutal put-down, she added: "I think I have hit on why the SNP are losing the case for independence."
The back and forth came just a week after the Commons Leader accused the party of having "wrecked the education system".
She accused the SNP of conducting "horrific" behaviour towards its own elected representatives and "bile fuelled rants".
WATCH: Penny Mordaunt accuses the SNP of 'bile fuelled' rants
Referring to last weeks comments, SNP MP Dierdre Brock told the Commons: "Firstly, a word that of thanks. The leader of the House has described me in this chamber and on social media as sanctimonious, delusional, treacherous and slopey shouldered.
"I can't say how much this kind of language from a Tory is a badge of honour for me and Scotland, so I am very grateful.
"Even more, her comments last week about Scotland's drug policies were literally front page news. The Daily Record describing them as 'an odd rant', one of the more positive responses. One correspondent asked, 'Why does Penny hate Scotland so much? was she scared by the bagpipes as a child?'
"We certainly look forward to the leader's reply to that."
She added: "And her answer illustrated very comprehensively, I'm afraid, the attitudes and contempt on that side of the house for the people of Scotland.
"Maybe she needs to refresh her government's growing army of scriptwriters in Edinburgh paid for of course by taxpayers' money. No more fat-free, out-of-date Trumpian rants please."
In a furious response, Mordaunt said: "Let me add some more adjectives to the ones the honourable lady describes because the SNP really have surpassed themselves this week in terms of being self-obsessed, self-pitying, and self-delusional.
"I think I have hit on why the SNP are losing the case for independence.
"Surely, if Scotland were to take this leap, they would want their leaders to be the sort of people that would step up and take responsibility and work hard to improve their opportunities. "But despite the Scottish Government being one of the most powerful devolved administrations in the world, it can't accept responsibility for anything.
"Given that they have been in power for 16 years, and every single one of those years, their budget has been 20 per cent higher than England, who does she think it is that is responsible for Scotland's declining A and E performance, increased waiting times, 70 per cent hike in drug-related deaths, 10 per cent increase in the attainment gap, the 10 years they've been missing their cancer targets and their housing targets or rising crime or soaring violence in schools, or the lowest police numbers since 2008. And the 1,700 fewer teachers.
"Who does she think it is that is responsible for the fact that some police forces are not even investigating certain offences and they're warning them that soon they will not be able to attend callouts?
"Who does she think it is that is responsible for plummeting international rankings in maths, literacy and science?
"Who does she think it is that has snaffled more than half of the 1 billion in extra tax Scottish residents have to pay which never reaches public services.
"And she talks about Scottish schoolchildren - who is it that has chosen to pay so much less to Scottish schools per pupil than anywhere else in the UK?
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Dierdre Brock hit out at Mordaunt in the Commons
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"Given that the Autumn Statement has given the Scottish Government and additional 545 million pounds and we are about to hear their budget, I think it's a pretty safe bet that it will not be spent wisely.
"By all means the honourable lady can send me what she likes. But I have to say there is a trend here.
"And I think that Scottish SNP supporters will soon be outnumbered by the numbers of pandas in her local zoo."