The leader of the SNP at Westminster told the BBC’s Today programme that, although he “feels for her,” Ms Ferrier should “consider her position.”
Last night it emerged that Ms Ferrier, MP for Rutherglen and Hamilton West, had travelled to Parliament after developing Covid-19 symptoms, and returned to her constituency on public transport after testing positive for the virus.
Asked if he wanted Margaret Ferrier, who has had the SNP whip suspended, to resign, Mr Blackford told BBC Radio 4’s Today programme: “This is a very serious situation.
“That we have been living with this Covid for a number of months. Now, people are making enormous sacrifices.
“And MPs have to be judged to the highest standards.
“And, we have a situation here that not only has the guidance been broken, but the law has been broken.
“And, I would simply say to Margaret that people will expect her to reflect on the situation that she has put herself in.”
“And it’s clear that Margaret travelled to London having had a (Covid) test, and having then been informed that she had tested positive, did the journey in reverse.
“That is not only wrong, it is a breach of the law.”
“This is regrettable,” he added, “she is a woman who is much loved within the parliamentary group, and I feel for her.
“But she has created a set of circumstances that are simply not acceptable.
“And, rightly, there is anger right across the country that people have made enormous sacrifices, people have seen their loved ones dying, and our leaders, our parliamentarians, our public figures, have got to be held to the highest standards.”
Mr Blackford joins a chorus of voices heavily critical of Ms Ferrier’s actions.
This morning, Scottish Conservatives leader Douglas Ross branded her decision to travel between London and Glasgow on a train while suffering Covid-19 symptoms as “reckless and dangerous”.
Speaking to Times Radio, Mr Ross said: “We expect politicians to lead by example and follow the guidance we are setting – we are law-makers.