Mandy Rhodes, the editor of Holyrood, said the Respect party MP's remarks that Assange was guilty of just "bad manners" by failing to ask permission to have sex with a sleeping woman, had left her "frankly gobsmacked".
Rhodes said she had not always agreed with Galloway's views in the past but had respected his integrity, his role as an "effective thorn in the side of the establishment", and his stance on Iraq.
However, she said it was impossible for him to continue his column following his remark that having sex with a sleeping woman was "not rape as anyone with any sense can possibly recognise it" if she had already had sex with that man.
"There is no excuse, ever, for sex without consent, and regardless of the details of the Assange case, Galloway's comments and inappropriate language about rape per se are alarming," Rhodes said in a statement on the magazine's website.
She added: "I had hoped he might have taken the last 24 hours to reflect on his judgment and perhaps make some kind of public apology – but that has not been apparent, far from it. So, it is with some very genuine regret that I have asked him to no longer write his column for the magazine."
Already a weekly columnist for the Record newspaper, Galloway, the MP for Bradford West, had been hired recently to write regular columns for Holyrood, a fortnightly magazine covering the devolved parliament in Edinburgh and mainstream Scottish politics. He took up the role after the former Scottish National party MP Jim Sillars stood down as a columnist on health grounds.
He had written five columns before Rhodes emailed him and his press adviser, Ron McKay, on Wednesday morning to say he had been sacked.
McKay said Galloway was in Indonesia and might be unaware of this latest development. After reading Rhodes's statement, McKay said: "There's not much to say really, is there?"
Galloway has been roundly condemned by senior figures in his own party, by rape crisis groups and other MPs, after saying in a video blog posted last week: "Some people believe that when you go to bed with somebody, take off your clothes, and have sex with them and then fall asleep, you're already in the sex game with them.
"It might be really bad manners not to have tapped her on the shoulder and said, 'do you mind if I do it again?'
"It might be really sordid and bad sexual etiquette, but whatever else it is, it is not rape, or you bankrupt the term rape of all meaning."
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