Theresa May has been accused by Labour of a “calculated” attempt to mislead the House of Commons and of breaching the ministerial code.
Government Chief Whip Julian Smith and Tory chairman Brandon Lewis are under intense pressure to quit in a row over claims they adopted murky tactics during a crucial Brexit vote.
Lewis, the chairman of the Conservative Party, was not supposed to vote on key amendments to the Trade Bill on Tuesday as he had an agreement with Lib Dem Jo Swinson - who is on maternity leave - not to. But he did.
His votes helped Theresa May to narrowly avoid a defeat which could have triggered calls for a vote of no confidence.
The prime minister told MPs on Wednesday this was “done in error”. Andrea Leadsom, the Commons Leader, told MPs it was a “mistake”.
But in a letter to Mark Sedwill, the acting Cabinet Secretary, Labour’s shadow Cabinet Office minister Jon Trickett said the reports the agreement was broken on purpose showed there was “an orchestrated attempt by the government to cover up their actions”.
Trickett said of May and Leadsom’s comments in the Commons: “We now know that these statements were false and I would argue calculated to mislead the House of Commons.
“These comments, as well as public statements issued by and on behalf of the Chief Whip, constitute a breach of the Ministerial Code as above, and should be investigated immediately.
“Please confirm as a matter of urgency that this has been referred to the Director General for Propriety and Ethics.”
Conservative MPs have publicly spoken out against the move. Anna Soubry, a leading Remainer, said: “If true this is appalling and those responsible must resign. If we cannot behave with honour we are nothing.”
Conservative Brexiteer Peter Bone said he was “very concerned” to hear that a pairing had been broken.
Another Tory MP, Heidi Allen, said: “No matter how tough the going gets, principle, integrity and standards matter. Without those, what’s left?”