A Conservative MP has defended Mark Field, as Theresa May was urged to sack the foreign office minister for grabbing a climate change protester around the neck and forcing her out of a black-tie dinner.

Mr Field was accused of “horrific” behaviour and of “behaving in a violent way”, after the footage emerged of his reaction to the peaceful protest at the City of London event.

His future was cast into further doubt when the Conservative party chairman said he was “astonished” and confirmed an investigation would be launched.

But Peter Bottomley insisted Mr Field had done nothing wrong, saying: “The woman clearly was trying to create a fuss.”

He added: “I think there's no reason to criticise Mark Field. Of course it wasn't an assault, it was a reversal of direction.”

Tory MP Mark Field manhandles climate protester: In pictures Show all 10 1 /10 Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field marches a protester out of the hall after pushing her up against a pillar as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field turns to push a protester up against a wall as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field pushes a protester up against a wall as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field pushes a protester up against a wall as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field pushes a protester up against a wall as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field grabs the neck of a protester as members of Greenpeace disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field marches a protester out of the hall after pushing her up against a pillar as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field marches a protester out of the hall after pushing her up against a pillar as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field marches a protester out of the hall after pushing her up against a pillar as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News Tory MP Mark Field manhandles climate protester: In pictures Tory MP Mark Field marches a protester out of the hall after pushing her up against a pillar as Greenpeace protesters disrupt a speech by chancellor Philip Hammond at Mansion House in London on June 20 ITV News

But Greenpeace, which organised the protest, said it was “shocked”, arguing the protester – who was pushed against a column at the Mansion House – had merely wanted to discuss the climate crisis.

Dawn Butler, Labour's shadow women and equalities minister, demanded Mr Field go, tweeting: “This is horrific. He must immediately be suspended or sacked.”

Sarah Wollaston, the former Conservative MP, now sitting as an independent, said it was “absolutely shameful, a male MP marching a woman out of a room by her neck”.

And Ed Davey, the Liberal Democrat leadership contender, said: “Mark Field needs to resign from government. No ifs, no buts about this. If he doesn't he must be sacked.

“The sight of some penguin-suited Tory minister behaving in a violent way towards a female Greenpeace activist absolutely stinks. Shame on you, Mark Field.”

Questioned about the incident, Brandon Lewis, the Tory chairman, admitted: “When you look at that video it's very hard not to be astonished by what you've seen.”

Told, on ITV’s Good Morning Britain programme, it was “not a good look”, Mr Lewis agreed, saying: “Not at all.”

Mr Field has apologised to the woman for “grabbing her” and referred himself to the Cabinet Office for an investigation.

He claimed he reacted “instinctively” and said he was worried she may have been armed.

Dozens of activists disrupted the beginning of a speech by Philip Hammond, the chancellor, dressed in suits, red dresses and sashes, and refused to leave.

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Video footage showed the minister jumping out of his seat and stopping one female protester, before marching her out of the room holding her neck.

One of its climate campaigners, Areeba Hamid, said: “The protester in question was hoping to discuss climate change and the economic reforms we need with the financiers and bankers at the dinner.