The SNP is under fire after an MP admitted to breaking coronavirus rules by travelling to parliament after developoing symptoms and returning to Scotland by train after testing positive for the virus.

Margaret Ferrier apologised on Thursday evening for her actions, which have been described as "utterly indefensible" by First Minister Nicola Sturgeon.

The MP is facing calls for resignation from colleagues in her own party.

READ MORE: Politics LIVE blog with the latest news and updates on Margaret Ferrier

Labour suggested the party covered up knowledge of Margaret Ferrier’s actions after it emerged they knew of her diagnosis a day before she disclosed it on Thursday evening.

But SNP's Westminster leader Ian Blackford admitted on Friday that he had learned of her actions on Thursday morning - hours before she made her statement to the public.

He told BBC Radio 4's Today programme that the whip was informed about the diagnosis on Wednesday, and Mr Blackford was made aware of the extent of her actions on Thursday morning.

READ MORE: Timeline of Margaret Ferrier's movements as she breached Covid-19 rules

He asked the MP to “reflect on her situation” after she admitted breaking self-isolation rules by travelling to Parliament after developing coronavirus symptoms and then taking a train back to Scotland having tested positive.

Asked if he wanted Margaret Ferrier, who has had the SNP whip suspended, to resign, Mr Blackford said: “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.

READ MORE: Nicola Sturgeon calls the actions of Margaret Ferrier 'utterly indefensible'

“And, I would simply say to Margaret that people will expect her to reflect on the situation that she has put herself in.”

The Rutherglen and Hamilton West MP said she took a test on Saturday afternoon after experiencing “mild symptoms”, meaning she should have self-isolated, before travelling by train to London on Monday having felt better.

She spoke in the coronavirus debate in the House of Commons on Monday and, by her account, tested positive for Covid-19 that evening. She did not make clear whether she received the result before or after she spoke.

In a statement, she said she travelled home to Glasgow on Tuesday, where she has been self-isolating ever since.

Scottish Labour leader Richard Leonard said: "I wish Margaret Ferrier a speedy recovery. But her reckless actions have rendered her unfit for public office.

READ MORE: SNP MP Margaret Ferrier travelled from London to Scotland by train after positive result for coronavirus

"Somone who has so outrageously flouted the laws that she has asked her constituents and the wider public to live by should no longer be voting on these laws. She has forfeited her right to be an MP and should resign immediately and force a by-election.

"Nicola Sturgeon and Ian Blackford must now state when they became aware of the breaches, and make public any internal party conversations that have already taken place about this case."