Conservative MP Michael Fabricant has apologised after tweeting that he might punch a female journalist in the throat.
Fabricant made the comments about leftwing journalist Yasmin Alibhai-Brown after she clashed with rightwing commentator Rod Liddle on a television news programme.
He tweeted: "I could never appear on a discussion prog with @y_alibhai I would either end up with a brain haemorrhage or by punching her in the throat."
The comments sparked a furious backlash.
A Conservative spokesman said: "Mr Fabricant's comments were completely unacceptable, in poor taste and he should immediately apologise."
Gloria De Piero, shadow minister for women and equalities, said: "Michael Fabricant's tweet is utterly appalling and he must apologise personally to Yasmin Alibhai-Brown immediately.
"It is unacceptable that views like this persist in the Conservative party. David Cameron needs to be clear about this and set out what action he will be taking."
The Labour frontbencher added on Twitter: "What a disgusting thing to say @Mike_Fabricant. I think you shld apologise to @y_alibhai."
Liberal Democrat peer Lady Hussein-Ece asked Fabricant: "Really? – You an MP want to 'punch a woman in the throat?'"
Fabricant, a former Tory vice-chair, later tweeted an apology. "So just for the avoidance of any doubt: I am v sorry for tweet," he said. "It was wrong to joke abt punching + I completely withdraw and apologise."
Alibhai-Brown told LBC radio: "Is this his apology? Well, he can stuff it. I don't want to talk to him at all.
"This is his apology? As an elected member of parliament [he] thinks it's OK to say that he would punch me in the throat because he didn't like what I said to a man who is perfectly capable of taking anything: Mr Rod Liddle; he's not a soft little kitten.
She dismissed Fabricant's attempts at an apology. "He has not apologised. I do not call this an apology. This is him trying to get out of a difficult situation and he's actually making it worse."
Alibhai-Brown, a Muslim who came to Britain from Uganda in 1972, said she felt like Fabricant was "encouraging" people who have previously threatened violence against her. "These guys find us unbearable," she added. "I think they still think Asian women should be their ayahs, their nursemaids, or selling them takeaways. We can be out here being assertive."
Over a series of tweets, Fabricant attempted to make amends for the Alibhai-Brown comments, telling Alibhai-Brown she was "utterly infuriating" but he would not have actually punched her.
He wrote: "Just out of dentist. 1 It appears that some people who don't know me think I actually go round punching 'in the throat'. Not true.
"2. If anyone believes I would seriously threaten someone with violence, I of course withdraw and apologise.
"3. I am afraid I know I would get v angry if I had been on the Ch4 debate last night. Glad it was Rod Liddle and not me!"
To Alibhai-Brown, he said: "Sorry @y_alibhai if you actually thought I would punch you. I actually don't do that sort of thing. But you are utterly infuriating! xx".
Fabricant was also criticised for retweeting a comment saying the journalist should be deported.
Other Twitter users pointed out that Fabricant had once been photographed with a sign stating: "Real men don't hit women."
Fabricant, a former Tory whip, has long been a thorn in the side of the Conservative leadership and regularly courts controversy on Twitter. When it emerged that Malaysia Airlines flight MH370 had gone missing, he tweeted: "It occurs to me: All our good news on the economy is currently as submerged and lost as the Malaysian Airlines flight recorder..."
The MP, whose Twitter avatar is a character from figure-skating comedy Blades Of Glory, also joked about having a relationship with a llama.
He tweeted a link to a Times diary story which reported that he was told: "No 10 says it has enough problems with the party in getting equal marriage through without you advocating bestiality," adding the comment: "Oh dear. I have told the llama story to one too many ppl. But I couldn't keep a straight face!"
He was sacked as a party vice-chair in April following his criticisms of the HS2 rail scheme and the Maria Miller expenses row. Earlier today he retweeted a message that said the "conservative party are a bunch of tossers, except you Mike" adding: "Now I am no longer Vice Chairman, I can RT that lol!"
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