Writing in The National, Black said she had been “horrified” and “afraid of the rhetoric” from the Tory conference in Birmingham.
“The Conservative Party’s mask as ‘a party of the common people’ has slipped to reveal the xenophobic, often racist, nationalist, ugly face beneath,” she writes.
“The very fact that they now openly share the same values and policies as Ukip says it all.”
She adds: “The Conservative Party’s conference has unleashed ugly and downright scary rhetoric that I was brought up to believe was to be left in the past. I am not exaggerating when I say that the policies being brought forward are reminiscent of early 1930s Nazi Germany.”
Last week, First Minister Nicola Sturgeon said she would support Scottish firms which ignored any new UK rules on revealing how many foreign workers they hire.
The First Minister said she would stand “full square behind” any Scots company which snubs the new rules unveiled by Home Secretary Amber Rudd this week amid claims of racism.
She said: “What I found particularly offensive was the idea that companies would be named and shamed for the foreign workers they employ as if there was something shameful about employing workers from other countries. It is absolutely disgraceful.”
She added: “Well, I think it’s about time the Tories stood up and said this, that it’s definitely something they will not ever do because it would be downright disgraceful and disgusting, and this government would have absolutely nothing to do with it.”
Ms Rudd’s proposals would see firms being forced to disclose what percentage of their workforce is non-British as a way to encourage them to hire more locals. The Home Secretary believes firms are “getting away” with not training enough British workers and the existing resident labour test - which requires firms to advertise vacancies in the UK for 28 days before looking outside the EU - should be toughened up.