A member of the crowd captured the incident on their mobile phone
A man in his 30s has been arrested on suspicion of assaulting two female Labour Party volunteers in east London.
Former deputy Labour leader John Prescott said the incident happened when two men - one in a John Prescott mask - tried to attack him.
Local Labour candidate Jim Fitzpatrick said it was "disgraceful".
The Conservatives say they have launched an investigation into the incident following allegations that the men were party members.
Mr Prescott wrote on his twitter page that a man "attacked two women in scuffle trying to get me".
"I'm alright after the scuffle. He didn't touch me but I was worried about the ladies. He was wearing a John Prescott mask! Bizarre".
Following allegations that the two men involved were the Conservative council candidates, Tory chairman Eric Pickles replied to Mr Prescott via Twitter.
He wrote: "Glad you are ok hope no one hurt - I have asked for a Party investigation - physical force is unacceptable in politics".
A Conservative spokesman said: "We do not accept or tolerate aggressive behaviour while campaigning for this party.
"We have opened an investigation into this incident, as a result of which those involved have had their membership suspended pending the outcome of this investigation."
A Metropolitan Police spokesman said: "At about 2pm a disturbance occurred in Chrisp Street, Poplar.
"Two men were spoken to by police about their behaviour. One was arrested on suspicion of assaulting two women aged 46 and 61.
"The man, aged in his 30s, is now in custody at an east London police station. The women declined medical attention."