A foreign office minister is facing demands he be sacked after he was filmed forcefully grabbing a climate change protester who gatecrashed an event at London's Mansion House.
Bankers and politicians had gathered at the event last night to hear speeches by Chancellor Philip Hammond and the Bank of England's governor Mark Carney.
But just as the speeches began, 40 protesters from Greenpeace entered the room, dressed in red.
As one of the women walked past Tory frontbencher Mark Field, he stood, pushed her against a nearby pillar and grabbed her by the back of the neck before frogmarching her out of the room.
A City of London Police spokesman said: "We have received a small number of third party reports of an assault taking place at the event.
"These reports are being looked into by police."
Mr Field has referred himself to the Cabinet Office for investigation and has apologised "unreservedly" to the protester.
In a statement he said: "A major security breach occurred at the dinner I attended last night when a large number of protesters suddenly and noisily stormed into Mansion House.
"In the confusion many guests understandably felt threatened and when one protester rushed past me towards the top table I instinctively reacted.
"There was no security present and I was for a split-second genuinely worried she might have been armed.
"As a result I grasped the intruder firmly in order to remove her from the room as swiftly as possible. I deeply regret this episode and unreservedly apologise to the lady concerned for grabbing her but in the current climate I felt the need to act decisively to close down the threat to the safety of those present.
"In view of the publicity around this incident I am referring myself to the Cabinet Office to examine whether there has been a breach of the ministerial code, and will of course co-operate fully with their investigation."
His actions towards the protester have polarised opinion, with critics rounding on him while some colleagues have rallied to his defence.
Rebecca Newsom of Greenpeace said: "I don't see any justification for the kind of violent behaviour we saw from his last night.
"It's and extremely shocking and concerning state of affairs. I think the Conservative Party and he personally need to look hard into this and actually review whether that kind of behaviour is appropriate for anyone let alone somebody in public office."
Tory Environment Minister Therese Coffey told Sky News: "I am very conscious the video doesn't look great.
"I think Mark acted instinctively.
"He's referred himself to the Cabinet Office about whether he breached the ministerial code. I know that Mark has already apologised.
"I think it is important now that inquiry is undertaken."
She added: "I think it's unfortunate the protester was able to get passed security."
Tory MP for Lewes Maria Caufield tweeted: "In this age where politicians have been murdered, jokes are made about throwing acid at us and we have all been threatened , no one knows what her motives were.
"If she had been carrying a weapon @MarkFieldUK would be hailed a hero now."
Conservative MP Johnny Mercer, a former soldier, tweeted: "Honestly? Try being in our shoes in the current environment. He panicked, he's not trained in restraint and arrest, and if you think this is 'serious violence', you may need to recalibrate your sensitivities.
"Calm down, move on, and be thankful this wasn't worse."
But Labour MP Dawn Butler, who is shadow secretary of state for women and equalities, described footage of the incident as "horrific".
She tweeted: "He must be immediately suspended or sacked. Due to violence against women.
"I'm sure I'm not the only one who is wondering why no one intervened. So much violence does not seem justified. An investigation needs to take place as soon as possible."
Labour MP Jess Phillips tweeted: "Every MP has to deal with protest and conflict, it is done with words. To watch this is so so awful."
Mayor of London Sadiq Khan tweeted: "It is truly shocking to see this kind of behaviour from an MP.
"Violence against women is endemic in our society and this behaviour is unacceptable. He should consider his position."
However, Tory MP Sir Peter Bottomley said Mr Field had done nothing wrong, adding: "The woman clearly was trying to create a fuss.
"Most viewers would say it's good that she didn't succeed."