Boris Johnson has been accused of being "corrupt" following allegations he attempted to get his wife Carrie Johnson a £100k job in the foreign office when he was foreign secretary.
The claims emerged in The Times on Saturday, before the article was removed from later print editions.
Number 10 has since admitted that they contacted The Times regarding the story before it was taken down.
Mrs Johnson has denied the allegations. “These claims are totally untrue,” her spokesperson said on Monday.
Chris Bryant, Labour MP and chair of the parliamentary standards committee, said on Twitter on Tuesday: "It is manifestly corrupt to appoint your lover as a [special adviser]."
Replying to a Tweet in support of the prime minister's actions from Tory MP Michael Fabricant, Bryant went on: "She wasn’t his wife. He had another wife at the time. That’s their business.
"But he tried to circumvent open and fair recruitment processes at the FCO for his lover. This is corrupt. And you endorse it."
Downing Street has refused to comment directly on the situation, with the PM's spokesperson telling reporters: "As a function of my role, I don’t comment on what the prime minister did before he was prime minister.
He instead pointed to existing denials from Mrs Johnson.
At the time, the prime minister was married to Marina Wheeler but was in a romantic relationship with his current wife Mrs Johnson - who then went by her maiden name of Symonds.
Dominic Cummings, the PM's former top adviser and now arch critic, has also claimed the story is true.
"The 'missing story' (pulled by The Times after Number 10 call Friday night) is true," he posted on Twitter. "Walters repeatedly published accurate stories, e.g on illegal donations. The Times pathetic to have folded & should reverse ferret.
"Truth is worse! [Mr Johnson] wanted to appoint girlfriend to gvt job in Q3 2020 too. [sic]"
On Tuesday Number 10 also failed to deny claims published by The Mirror that Mr Johnson had discussed with aides appointing his wife as an ambassador in the run up to COP26, and that he had discussed making her a communications director for the Duke and Duchess of Cambridge.
The controversies come after string of scandals surrounding Johnson's adherence to the ministerial code.
Last week, the prime minister's ethics adviser Lord Geidt resigned over concerns about Johnson's potential violations of international law.
"I was tasked to offer a view about the government's intention to consider measures which risk a deliberate and purposeful breach of the ministerial code," wrote Geidt in a letter.
"This request has placed me in an impossible and odious position."
He added: "A deliberate breach, or even an intention to do so, would be to suspend the provisions of the [ministerial] code to suit a political end… I can have no part in this."
Geidt also told The Telegraph on Monday that the controversy over the issue of Mrs Johnson's job offers "could be ripe for investigation" and that the incident could be a matter for his successor.