Boris Johnson and Jeremy Corbyn were involved in a series of angry exchanges over racism and anti-Semitism in the final TV debate of the General Election campaign.
The Prime Minister accused Mr Corbyn of a “failure of leadership” in his handling of anti-Semitism in the Labour Party.
The Labour leader shot back that he never used racist language and that he hoped Mr Johnson regretted his past comments.
Appearing before a live BBC studio audience in Maidstone, the two leaders clashed over Brexit, the NHS and terrorism.
But the sharpest exchanges were prompted by a question about their response to the issues of Islamophobia and anti-Semitism.
Mr Johnson said it was “extraordinary” the Chief Rabbi had felt the need to speak out during an election campaign about his fears for his community if Mr Corbyn became prime minister.
The Labour leader insisted there was “no place” in his party for anti-Semitism, adding in an apparent reference to Mr Johnson’s past comments: “I do not ever use racist language in any form to describe anybody in this world or in our society.”
Mr Johnson replied: “Mr Corbyn I am sure is very well-intentioned but in his handling of this particular issue, his unwillingness to take a stand to stand up for Jewish people in the Labour Party, his unwillingness to protect them, to put an arm round them, is in my view a failure of leadership.”
Mr Corbyn retorted: “The failure of leadership is when you use racist remarks to describe people in different countries or in our society. I will never do that and my will never do that.
“I hope the prime minister understands the hurt that people feel when they hear remarks and articles that he has written in the past. I hope that he will regret those.”
Mr Corbyn did not specify which comments he was referring to but Mr Johnson has been widely criticised for articles he wrote referring to “piccaninnies” and likening Muslim women in burqas to letterboxes and bank robbers.
A snap YouGov poll of 1,322 viewers following the debate narrowly gave victory to Mr Johnson by 52% to 48%, although Mr Corbyn was judged the more trustworthy by a margin of 48% to 38%.
With less than a week to go to polling day on Thursday – and Labour trailing in the overall polls – the findings suggest that the debate is unlikely to prove a game-changer.
Mr Corbyn dismissed an accusation by Mr Johnson that in Diane Abbott he would appoint a home secretary who wanted to abolish MI5.
“There are no plans whatsoever to disband MI5 or any other part of the security services,” he said.
The Prime Minister sought to widen the discussion to suggest that the current bitterness in politics was down to the failure of politicians to deliver on Brexit.
He attacked the Labour leader’s commitment to stay “neutral” in a planned Labour final say referendum on the EU.
“The scratchiness of politics, the bitterness, the acrimony is a function of our inability to get Brexit done,” he said.
“You cannot be neutral on questions like this any more in my view you can try to lead this country and be neutral on the issue of Brexit.
“It is a failure to take a stand, to have a point of view that in the end will cost this country gravely and deeply.
Earlier, the Labour leader warned of “chaos” and “huge job losses” if a Tory government was unable to get a free trade deal with the EU by the end of the year.
He highlighted leaked Treasury documents released earlier in the day by Labour which he said showed Mr Johnson’s withdrawal agreement meant there would be customs checks and restrictions on trade between Britain and Northern Ireland.
“He spoke at the DUP conference and said there would be no restrictions whatsoever. We now know there are restrictions. He could and should have said that at the time,” he said.
The Prime Minister retorted that the claims were “not true”.
Mr Johnson also brushed off an intervention by former prime minister Sir John Major who suggested he would back former Tory MPs now standing as independents after having the whip withdrawn.
“Unlike Mr Major, I lead a party that is now totally united,” he said.