Sir Keir Starmer today admitted footage of a suspended Labour MP punching a man and continuing to hit him on the ground was shocking.
The Prime Minister was quizzed about CCTV, obtained by the Mail, showing Mike Amesbury in a street brawl in the early hours of Saturday morning.
The MP for Runcorn and Helsby, who has been stripped of the Labour whip over the incident, has said he will co-operate with any inquiries.
Sir Keir told a pre-Budget press conference this morning: Ive seen the video footage, its shocking.
He added that party bosses had moved very swiftly to suspend Mr Amesbury as a Labour MP and party member after the CCTV footage was published.
But the PM declined to comment further after being asked whether Mr Amesbury, who will now sit as an independent MP, should quit the House of Commons.
There is now a police investigation and, in the circumstances, youll appreciate there is not much more I can say about that, he said.
Cheshire Police have confirmed a 55-year-old man was voluntarily interviewed under caution in relation to the incident.
Officers were called to reports of an assault in Frodsham at 2.48am on Saturday.
Mike Amesbury, the MP for Runcorn and Helsby, lost the Labour whip yesterday after he was filmed punching a man and continuing to hit him on the ground
Cheshire Police confirmed a 55-year-old man had been voluntarily interviewed under caution in relation to the incident
Sir Keir Starmer told a pre-Budget press conference this morning: Ive seen the video footage, its shocking.
A Tory former minister whose father was killed by a single punch has condemned Mr Amesbury over the horrendous video of his street brawl.
In a social media post last night, Dehenna Davison made reference to how her father was killed by a single punch from a man when she was just 13 years old.
She wrote: I have just seen the horrendous footage of Mike Amesbury punching a man to the ground in the street.
The police are investigating, and I am sure the full facts will emerge soon.
I have spent years working with One Punch UK to raise awareness of the dangers a single punch can cause.
My own Dad died instantly from a single punch, and we have worked with countless families who have lost loved ones through these mindless acts.
A split-second decision can end and ruin lives. Such violence - whatever the background to the altercations - is never and should never be justified.
Ms Davison, a former levelling up minister who stood down as Bishop Auckland MP at the general election, added: People in positions of responsibility should always need to remember that their actions set an example.
In democracies, we settle disputes with words, not with violence. Thuggish, violent behaviour is not the example any MP should be setting.
Tory former minister Dehenna Davison warned of the dangers of mindless acts after shocking CCTV footage, obtained by the Mail, showed Mr Amesbury attacking a man
In a social media post, Ms Davison made reference to how her father was killed by a single punch from a man when she was just 13 years old
Mr Amesbury has said he will co-operate with any inquiries
Cabinet minister Pat McFadden this morning admitted the CCTV footage of Mr Amesbury was very graphic.
The Chancellor of the Duchy of Lancaster told Sky News: Hes been suspended by the Labour Party, that also means hes not a Labour MP at the moment while the police investigation takes place.
Ive seen the video, there is a police investigation, I think its important that that runs its course.
Questioned further about the clip, Mr McFadden added: The video is very graphic, the police will look into that, Im sure theyll take it into account and theyve got to reach their conclusion.
Labour said yesterday that Mr Amesbury had been suspended pending an investigation into the incident.
A party spokesperson said: Mike Amesbury MP has been assisting Cheshire Police with their inquiries following an incident on Friday night.
As these inquiries are now ongoing, the Labour Party has administratively suspended Mr Amesburys membership of the Labour Party pending an investigation.
It has since been revealed how Mr Amesbury attended a meeting with the local police commissioner hours before the shocking incident
Cheshire Police said a 55-year-old man had been released pending further inquiries.
The CCTV captured Mr Amesbury and another man stood facing each other before the MP punched the other and continued hitting him on the ground.
It is not clear from the video what happened in the moments beforehand.
It comes after different footage posted on social media on Saturday showed the MP shouting and pointing his finger at a man lying in the street.
You wont ever threaten me again, will you? You wont ever threaten me again will you, he said.
Mr Amesbury said on Saturday that he will co-operate with any inquiries, but was determined to remain an open and accessible MP for our community after the initial footage circulated online.
He said in a statement: Last night, I was involved in an incident that took place after I felt threatened on the street following an evening out with friends.
This morning, I contacted Cheshire Police myself to report what happened during the incident.
I will not be making further public comment but will, of course, co-operate with any inquiries if required by Cheshire Police.
It has since been revealed how Mr Amesbury attended a meeting with the local police commissioner hours before the shocking incident.
He said he was listening to residents concerns and ideas for policing and community safety.