Suella Braverman has admitted to sending government emails to her personal phone.
The Home Secretary apologised for the breach in a letter to Dame Diana Johnson, the chairman of the home affairs select committee.
The full letter relates to issues around her resignation on October 19.
A day after Ms Braverman initially resigned Liz Truss also resigned as Prime Minister.
Her resignation was believed to be the final tipping point in Truss’ premiership.
But she was handed the role back a week later after Rishi Sunak took over as Tory leader and Prime Minister.
In a letter to the Commons Home Affairs Select Committee’s chairwoman Dame Diana Johnson, Ms Braverman apologised for the breach but admitted that she sent official documents from her government email to her personal email address on six occasions.
She said she had apologised to Rishi Sunak when she was reappointed as Home Secretary after he entered No 10 and publicly repeated that apology.
In her letter to Dame Diana Johnson, Braverman said the document she leaked was a four-page document was a draft written ministerial statement that contained ‘high level policy on illegal migration and legal migration proposals’
She wrote: ’I want the Home Affairs Select Committee to be reassured on the very important point about the nature of the document that I shared by mistake.
‘The draft WMS [Written Ministerial Statement] did not contain any information relating to national security, the intelligence agencies, cyber security or law enforcement. It did not contain details of any particular case work.
‘It did not contain any market-sensitive data as all the data contained in the document was already in the public domain. It was not classified as SECRET or TOP SECRET.’
She added: ‘In my appointment discussion with the new Prime Minister, I raised this mistake and apologised to him, and would like to do so again here.
‘I also gave the Prime Minister assurances that I would not use my personal email for official business and reaffirmed my understanding of and adherence to the Ministerial Code.’
Ms Braverman writes: ‘Following my referral and subsequent resignation, the Home Office conducted a review of my use of personal email and verified the above sequence of events.
‘The review also identified that within the period between 6th September and 19th October, I had sent official documents from my Government email to my personal email address on six occasions.
‘The review confirmed that all of these occasions occurred in circumstances when I was conducting Home Office meetings virtually or related to public lines to take in interviews.
‘Some of these meetings had been hastily arranged in response to urgent operational matters relating to Home Office priorities.
‘The review also confirmed that on no other occasions had my Special Adviser emailed my personal account in relation to official business.’
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