Rishi Sunak said he was “delighted” to reappoint Suella Braveman as Home Secretary just days after she was sacked for a security breach.
The Prime Minister told MPs that Ms Braverman had “accepted her mistake” and was part of a “united cabinet”.
But Labour leader Sir Keir Starmer said of “He’s so weak, he’s done a grubby deal trading national security because he was scared to lose another leadership election.”
Both Labour and the Liberal Democrats raised “national security” concerns and demanded a Cabinet Office investigation on Wednesday after Braverman’s return.
Cabinet Secretary Simon Case, the most senior civil servant, is “livid” over her swift return and “very concerned” about the breach, a source told the Times.
Liz Truss forced Braverman out after she breached the ministerial code by sending an official document to a Tory backbencher from a personal email.
Braverman, who had been in the role six weeks, said she made a “mistake” which she conceded was a “technical infringement” of the rules.
But questions remain about why she sent the document to fellow right-winger Sir John Hayes and how she accidentally copied in an aide to another MP, who sounded the alarm.
Sir Keir, speaking at Prime Minister’s Questions, asked: “Was his Home Secretary right to resign last week for a breach of security?”
Sunak replied: “The Home Secretary made an error of judgment but she recognised that, she raised the matter and she accepted her mistake.
“That is why I was delighted to welcome her back into a united cabinet that brings experience and stability to the heart of Government.”
Labour later secured an urgent question in the Commons and asked Braverman to appear before MPs to explain what had happened.
But Cabinet Office minister Jeremy Quin was sent out to answer the questions, saying: “The ministerial code allows for a range of sanctions where mistakes have been made. The Home Secretary recognised her mistake, raised the matter and stepped down. Her resignation was accepted by the then Prime Minister.
“Ministerial appointments are a matter solely for the Prime Minister.”