An investigation has been launched into the chaotic scenes in the House of Commons where Tory MPs were accused of “manhandling” their colleagues into voting.

Speaker Sir Lindsay Hoyle announced he has asked the Serjeant at Arms and other officials to investigate allegations made about incidents in the Commons on Wednesday night.

He will be meeting with senior party representatives “to seek an agreed position that behaviour like that described last night is not acceptable in all circumstances”.

In a statement to MPs, he said: “I remind Members that the behaviour code applies to them as well as to other members of our parliamentary community.”

The Speaker, who is in charge of ensuring order in the Commons, added that while MPs might have “very strong political disagreements” they must “treat each other courteously and with respect”.

His announcement came as confusion reigned over what happened ahead of an opposition day vote on fracking.

After the incident, the number of Tory MPs publicly calling for Ms Truss to go ramped up, with 14 in total by mid-morning on Thursday – more than double than the day before.

Many were upset about Wednesday night’s events and also the resignation of Suella Braverman as home secretary, with questions over why exactly she quit after she said she had sent a sensitive message from her personal email.

Transport Secretary Anne-Marie Trevelyan earlier said she was “shocked” to hear what happened during the vote.

She said she voted early so was not there when the chaos ensued but told Sky News’ Kay Burley at Breakfast programme: “It is never acceptable for people to be manhandled or bullied into voting.

“We have seen this happen before where whips perhaps over-egg their encouragement to get people to vote in the appropriate way. That is never right.

“The one thing that our parliament is so revered for around the world is that we allow each of us to vote with our conscience and indeed with our government on important matters.”

There was confusion just moments before voting started on Labour’s opposition day vote to ban fracking after MPs were told it was no longer a “vote of confidence in the government” – which the whips had said it was earlier in the day and told all Tory MPs they had to vote against the motion or face being suspended.

In the early hours of this morning, Downing Street sent a message to journalists saying a minister had been told “mistakenly” by them to say the vote was not a confidence vote, but they said Tory MPs were “fully aware” the vote was subject to a three line whip – where they can be suspended if they do not vote with the government.

But asked this morning if it was a confidence vote, Ms Trevelyan said: “No, yesterday was an opposition day debate and the Labour Party were trying to use a parliamentary tool to try and hijack the order paper. That is never acceptable.

“So what it was, was a very important vote to ensure that the government did not allow Labour to do that. It’s a tactic that has been used in the past. And previous governments have also always made sure that those votes are not won by the opposition.”

She added that those MPs who defied the whip will have discussions with the chief whips, but said there are often “specific constituency reasons or health reasons” for not voting with the government.

Labour MP Chris Bryant took a photo of a huddle of Tory MPs in the lobby looking confused.

He told Sky News: “There was a lot of shouting, there was a lot of speculating, pointing at people, jabbing at people, standing up to whips, squaring up to people.

“And then in a moment, maybe one or two MPs were effectively sort of frog marched through into the division lobby.

“It’s perfectly legitimate for the whips to try and persuade their members by force of reason to vote with them. But it’s not on to intimidate and bully.”

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