Boris Johnson "believes" that he reported meeting with Russian oligarch Alexander Lebedev (ex-KGB officer), a Foreign Office minister said.
Vicki Ford told MPs at first that Johnson, then foreign secretary in 2018, reported the meeting to him, even though no officials were present.
She corrected herself minutes later, stating that the PM "says he thinks that he mentioned this meeting with officials".
MPs are looking into Mr Johnson's awarding of a peerage Mr Lebedev's child.
Since the 2020 peerage was given to Evgeny Lebendev, controversy has been surrounding it. It was alleged by Tortoise Media (and the Sunday Times) that it was granted despite a risk to national security.
According to the Sunday Times, the peerage assessment by security services was withheld after Mr Johnson intervened personally. Johnson is a friend and longtime associate of Lord Lebedev.
The Commons Intelligence and Security Committee is currently investigating the matter.
Lord Lebedev is the owner of London Evening Standard, and a shareholder in Independent. He has denied that he poses a security threat to the UK.
At the Commons Liaison Committee, on Wednesday, the prime minister confirmed that he had met Alexander Lebedev. Alexander Lebedev bought the Evening Standard in 2009 with his son, but later left the company.
He stated that he had met the gentleman in question when he was mayor of London.
"On the occasion that you are referring to, if it was when I was foreign minister, then yes."
Shadow home secretary Yvette Cooper asked the Commons on Thursday about the national security implications for the meeting in Italy. She did not have security or officials present at the meeting, which took place "at the height of the Salisbury Poisoning Crisis" in April 2018.
Ms Ford stated that Alexander Lebedev had told her he had only met him "on very few occasions". She also said that she believed he had confirmed that he had met Mr Lebedev in person. He had reported the meetings to officials as necessary.
Chris Bryant, Labour's Labour representative, challenged Ms Ford to prove that Mr Johnson hadn't said anything about notifying officials. Ms Ford replied that it was her understanding that Johnson had reported the meeting.
She said, "I just received a note: apparently the prime minister states that he believes he mentioned this meeting with officials. "I am reporting what I was told."
Shadow home secretary claimed that Alexander Lebedev was sanctioned by Canada for being one of 14 individuals who enabled Russian President Vladimir Putin to wage war in Ukraine. However, the UK has not sanctioned him.
Many of Mr Putin's closest aides were KGB officers who worked for the Soviet Union's security service during the Cold War like Mr Lebedev.
Ms Cooper stated that the charges against the prime Minister are not about a lack or integrity, but a total disregard for basic national security as well as patriotic interests.
She asked whether the Foreign Office, Home Office, and security services knew of the meeting in advance, and whether a record was made afterward. She also referred to rumours about Mr Johnson being too drunk to recall the details.
According to the record of member's interest, Mr Johnson was invited by a guest but returned home on his own, she stated. "Who was that guest?" "Did that place him in a compromising situation?"
Lord Collins of Highbury (Labour foreign affairs spokesperson) called on Simon Case, Cabinet Secretary, to investigate. He said it wasn't enough for the prime minster to write to the liaison commission as promised Wednesday.
