Angela Rayner was spotted having a crafty cigarette amid tensions at the Labour Party conference after she called senior Tories 'racist, homophobic, scum'.
Deputy Labour leader Ms Rayner had refused to apologise for her remarks, delivered at a reception for activists.
Amid the fury over her statement, Ms Rayner was pictured smoking outside The Brighton Centre, where the Labour conference is being held.
Angela Rayner was spotted having a crafty cigarette amid tensions at the Labour Party conference after she called senior Tories 'racist, homophobic, scum'
Amid the fury over her statement, Ms Rayner was pictured smoking outside The Brighton Centre, where the Labour conference is being held
Sir Keir said he would speak to his deputy but it was a matter for her whether she apologised.
He told BBC One's The Andrew Marr Show: 'Angela and I take different approaches and that's not language that I would use.'
'Anyone who leaves children hungry during a pandemic and can give billions of pounds to their mates on WhatsApp, I think that was pretty scummy,' she told Sky News.
The Ashton-under-Lyne MP said her attack was made in the 'street language' of her northern working class roots.
In an apparent reference to Mr Johnson's history - including comparing burka-wearing Muslim women to 'letter boxes' - Ms Rayner said she would only apologise if the Prime Minister also said sorry.
'I'm saying the Prime Minister has said those things and acted in that way. If the Prime Minister wants to apologise and remove himself from those comments he has made that are homophobic, that are racist, that are misogynistic, I will apologise for calling him scummy.'
The Daily Mirror reported that at the event in Brighton on Saturday night, Ms Rayner said: 'We cannot get any worse than a bunch of scum, homophobic, racist, misogynistic, absolute vile... banana republic, vile, nasty, Etonian... piece of scum.'
Keir Starmer and Angela Rayner sat next to each other on the stage in Brighton this afternoon in an apparent bid to quell civil war rumours
The Ashton-under-Lyne MP said her attack was made in the 'street language' of her northern working class roots
To applause, she added she had 'held back a little'.
Conservative chairman Oliver Dowden said: 'At a time when the country is trying to pull together to recover from Covid, the last thing we need is the deputy leader of the Labour Party calling people 'scum' and yelling insults.
'We need to make politics better, not drag it into the gutter. Let's see if we get an apology.'
Foreign Office minister James Cleverly said voters would see a Tory Party which has had two female prime ministers and the 'most diverse government' and 'they'll know she's talking crap'.
Transport Secretary Grant Shapps said Ms Rayner's verbal attack was 'absolutely appalling', telling Sky News: 'There's no place in public life for that sort of language, that sort of behaviour.'
But veteran Tory MP James Gray also opened up the Conservatives to criticism after he suggested a bomb should be planted in Labour frontbencher Anneliese Dodd's office.
Mr Gray apologised for the 'foolish remark' that he wrote in a WhatsApp group with fellow Tory MPs.
Left-wing Labour veteran John McDonnell defended Ms Rayner, suggesting she should not have used the language she did but that 'deep down she's expressing the anger many of us feel'.
The former shadow chancellor told Sky's Trevor Phillips On Sunday: 'We've all been there, late at night, getting very angry about what's going on. What I like about Angie Rayner is that she's human.'
Current Labour frontbencher Lisa Nandy said it is 'completely up to' Ms Rayner whether she apologises over the remarks but conceded it is not the kind of language she herself would use.
The shadow foreign secretary told Times Radio: 'It's not my preferred choice of words. I'm not very interested in insulting the Tories. I just want to get rid of them.'