Allsopp vs Sugar. He's uncharitable. She's a lying cow!

It all turned ugly on Twitter yesterday. Will these TV celebrities ever make up?

An unseemly spat erupted yesterday between the television property show presenter Kirstie Allsopp and entrepreneur Alan Sugar, after Allsopp accused the peer of being "shockingly uncharitable" and mistreating his staff.

In a public message posted on Twitter, Allsopp tweeted: "Being asked whether I follow Alan Sugar. I worked with him on Sport Relief Does The Apprentice. His behaviour was shockingly uncharitable." Later she wrote: [sic] "There r words I don't use, but when it comes to Sugar & his treatment of the staff & crew involved... in any other work place he'd be Fired!!"

When Lord Sugar joined the army of twitterers this August, he admitted that he had been reluctant "in case I made a mug of myself". Yesterday he was being less cautious. In a series of increasingly rancorous posts, he retaliated against the Location, Location, Location presenter, branding her "a Lying cow" and calling her the [sic] "worst contestant on celeb apprentice ever".

Allsopp, who became a household name after presenting property programmes, and who has advised the Tories on housing policy, worked with Lord Sugar in the BBC's celebrity version of The Apprentice in aid of Sport Relief. She is believed to have fallen out with him after storming out of the show following an argument with Ann Summers' chief executive, Jacqueline Gold, over who should make a call to Richard Branson.

Sugar's first response yesterday was characteristically forthright: "What a Lying cow @KirstieMAllsopp was worst contestant in celeb apprentice ever having hissy fit all time very rude to Jacki Gold."

Then he got into his stride: "More lies from @KirstieMAllsopp said I was hard on and rude to production people in celeb apprentice , she is too far up Emma Freud ar..." and "@KirstieMAllsopp you are liar dont tweet lies about me by the way you were the worst celeb ever in celeb apprentice."

When asked by The Independent on Sunday whether it was a coincidence that this public argument on Twitter coincided with the start of a new series of The Apprentice, Lord Sugar said: "She started it. I didn't ask for her to open her big mouth and it's got nothing to do with drumming up publicity for The Apprentice. We don't need her for that.

"I stand by what I wrote; she's talking rubbish. She said I was so-called rude to the production team: that's not true. She also said that I was uncharitable, but I gave a lot of money to Sport Relief that she doesn't know about."

Lord Sugar has raised more than £2m from two charity specials of The Apprentice – for Comic Relief and Sport Relief. In a statement earlier this week, however, he said: "I wouldn't do another celebrity version. I'm not interested. I don't like the people."

Allsopp said yesterday that she would not be responding to his outbursts as she did not use Twitter at weekends. She added: "The best way of bringing an end to this sorry saga is a dignified silence."

Despite her insistence that she would not be tweeting again before Monday, she logged on shortly after speaking to the IoS to post a message about spending the evening in front of the television.