WASHINGTON (AFP) - Twitter was embroiled in controversy on Wednesday (July 20) after banning an editor at the conservative Breitbart website for fuelling a stream of abuse that drove Ghostbusters star Leslie Jones to quit the social network.

The ban on Milo Yiannopoulos, the website's tech editor known for provocative posts, sparked protests from his supporters but praise from others, while triggering debate over free speech on social media.

A hashtag war erupted between Yiannopoulos supporters united by the banner #FreeMilo and his critics - who rallied under #LoveForLeslieJ.

Yiannopoulos hit back at the ban saying "Twitter has confirmed itself as a safe space for Muslim terrorists and Black Lives Matter extremists, but a no-go zone for conservatives."

The suspension came a day after Jones, who is African American, said she was leaving Twitter after being bombarded by Internet trolls likening her to an ape among other racist slurs.

"I leave Twitter tonight with tears and a very sad heart. All this cause I did a movie. You can hate the movie but the shit I got today... wrong," the Saturday Night Live comedian and actress said late on Monday.

Twitter chief executive officer Jack Dorsey responded with a tweet to Jones saying he was "following" and asking her to contact him directly.

Yiannopoulos' Twitter account, which had more than 338,000 followers, was later blocked.

"People should be able to express diverse opinions and beliefs on Twitter," the company said in a statement.

"But no one deserves to be subjected to targeted abuse online."

Critics of Yiannopoulos said he incited his followers to bombard the actress with racial comments, while his supporters claimed he was targeted for his views.

Commenting on a tweet in which Jones said she had been called an ape, and "received a pic with semen on my face," Yiannopoulos responded: "If at first you don't succeed (because your work is terrible", play the victim. EVERYONE GETS HATE MAIL FFS."

His tweet reportedly triggered a torrent of abuse towards the 48-year-old Ghostbusters star who responded by taking screenshots and retweeting the slurs, saying they had made her "numb."

After being subjected to hours of harrassment from Yiannopoulos' supporters, Jones called him out: "@Nero you can say what you want about my work but when you support hate, that's not right. Wonder do your readers know you support hate!!"

Twitter's actions were set to further intensify a simmering debate on how social media platforms regulate offensive or inappropriate conduct.

One Twitter user, Sara Levine, welcomed the ban on Yiannopoulos, tweeting, "Racists shouldn't be allowed to silence others."

But Twitter user John Nolte responded, "Basically, the corporate fascists at @Twitter silenced someone for criticizing and mocking a rich and powerful movie star."

Both Twitter and Facebook have banned thousands of suspected Islamic militants for seeking to incite or celebrate violence, and have targeted users for harassment and insults.

But the platforms have been navigating a fine line, staying open to controversial views while keeping out violent or abusive content.

Matthew Ingram, a Fortune magazine writer who blogs for the Nieman Journalism Lab, suggested that this time, Twitter may have gone too far.

"I know this isn't going to be a popular opinion, but I don't think Milo said anything to Leslie Jones that deserves a permanent ban," Ingram tweeted.

Some analysts argue that social media platforms need to develop a code that mirrors constitutional free speech rights.

"Corporate platforms have, in many ways, taken on the role of the town square, or public sphere," said a blog post this year from Jillian York, a writer and activist who works with the Electronic Frontier Foundation.

"It is impossible to ignore the effect corporate limitations on speech can have on societies."

Mark Potok, a senior fellow at the Southern Poverty Law Center, which seeks to combat racism, maintained that social media firms have a right to set their own standards.

"These aren't First Amendment (constitutional) questions at all. Twitter and others are private corporations that have no obligation to allow these kinds of speech," Potok told AFP.

Potok said the lack of any policy led to chaos at the online service Reddit, which he said "turned into a hellhole for anyone who wasn't a hater" before it implemented guidelines.

"If these organisations say they have a no-hate policy, they ought to enforce it," he said.

Jennifer Lambe, a University of Delaware professor of communications specialising in free speech issues, said there is no easy answer for social networks.

"They can do whatever they want, but there could be a backlash if they start censoring things right and left," she said.

Danielle Citron, a University of Maryland law professor and author of a book Hate Crimes In Cyberspace, called the incident "a learning moment."

"I applaud Twitter for its approach in this area," Citron said. "If you chase people offline with racist and intimidating speech, that's too much. Twitter and other platforms are contributing to social norms on free expression."