Downing Street declined to say whether the Prime Minister knew about Louise Haigh’s criminal conviction and said that “further information” had come to light before her resignation.
Ms Haigh resigned as Transport Secretary after it emerged she pleaded guilty to a criminal offence related to incorrectly telling police that a work mobile phone was stolen in 2013.
It is understood the incident was disclosed to Sir Keir Starmer when she joined the shadow cabinet.
But Sir Keir’s spokesman repeatedly told journalists on Friday her resignation came after new information emerged.
“Following further information emerging, the Prime Minister has accepted Louise Haigh’s resignation,” the spokesman said.
He did not confirm whether Sir Keir had known about the conviction or specify what the new information was.
Asked if the PM believed Ms Haigh was completely candid when she was appointed to his shadow cabinet, the spokesman said he would not “get into individual conversations”.
He repeated that ministers are expected to adhere to the ministerial code, but did not say how the ministerial code applied to Ms Haigh’s resignation.
Asked whether she was asked to resign or offered to, he said: “She resigned.”
“The Prime Minister has accepted her resignation and she has acknowledged that the issue will inevitably be a distraction on delivering the work of Government,” he said.
Swindon South MP Heidi Alexander has been appointed to replace Ms Haigh as Transport Secretary.
Ms Haigh said that she was mugged in London and gave police a list of stolen possessions, including a work phone, when she reported the incident.
She said she later found the phone was still in her house.
In a letter to Sir Keir Starmer, she said: “I should have immediately informed my employer and not doing so straight away was a mistake.
“I appreciate that whatever the facts of the matter, this issue will inevitably be a distraction from delivering on the work of this government and the policies to which we are both committed.”
Ms Haigh pleaded guilty in court over the incident on the advice of a solicitor and magistrates gave her the “lowest possible outcome”, she said in a statement.
It is understood that the offence was “fraud by false representation” and that the conviction is now spent.
Ms Haigh’s employer at the time, Aviva, launched an investigation after she said that company mobile phones had been stolen or had gone missing on repeated occasions, the Times reported.
However, a source close to Ms Haigh disputed that multiple phones were involved.
She resigned from her job at Aviva, it is understood.
Ms Haigh does not believe a parliamentary colleague was behind the details of the conviction becoming public, the source said.
Ms Haigh has been Sheffield Heeley MP since 2015 and held a number of shadow ministerial and shadow cabinet roles before becoming Transport Secretary when Labour won the election in July. Before she entered politics she spent time as a special constable.