Chancellor Philip Hammond is facing calls for a Commons motion of contempt to be tabled against him over answers given to Parliament about Yemen by the Foreign Office when he was in charge of the department.
Labour MP Ann Clwyd has urged the action to be taken following corrections the Foreign Office issued amending statements and answers to parliamentary questions regarding breaches of International Humanitarian Law (IHL) in the war-torn country.
The original answers and statements claimed the British Government was confident Saudi Arabia's intervention in Yemen had corresponded with IHL.
But the corrections, released on the last day of the parliamentary term, said the Foreign Office had not carried out assessments that would have verified such claims.
The Government said the original statements resulted from error, and were not a deliberate attempt to mislead Parliament.
Ms Clwyd has written to the Speaker of the House of Commons asking him to refer the matter to the Committee of Privileges to see whether Mr Hammond, and two junior Foreign Office Ministers, were in contempt of Parliament.
The MP said: "For some time now, Saudi Arabia - using British bombs and planes - may have committed war crimes on Yemeni civilians.
"UK arms sales to Saudi Arabia topped £3.3 billion in the first year of the Saudi-led conflict in the Yemen.
"The UN Panel of Experts on the Yemen has listed 119 coalition exercises relating to war violations, with Human Rights Watch reporting 36 unlawful strikes - some of which may amount to war crimes - which have killed at least 550 civilians since the conflict began. We need to know the truth."
Amnesty International's Lucy Wake said: "We were as shocked as anyone when Philip Hammond slipped out that jaw-dropping admission that the Government had misled Parliament on a matter as grave as war crimes in Yemen.
"Ministers have spent more than a year ignoring or even trying to cast doubt on mounting evidence of the Saudi Arabia-led military coalition's indiscriminate attacks on Yemeni schools, hospitals and homes - all while the UK has sold billions of pounds worth of weapons to Riyadh.
"Late though it is, the Government now needs to announce an immediate halt to UK arms sales to the Saudi-led coalition and see that a full inquiry is set up into what has gone wrong with our arms exports control systems."