The Twitter account of Richard Spencer, one of the most prominent leaders of the alt-right movement, has been reinstated after being suspended for a month. Spencer's account, which reappeared on Saturday (10 December), was suspended in November as part of the company's crackdown on online harassment and abusive behaviour on its platform.

Spencer is the president and director of The National Policy Institute, a white nationalist think tank that describes itself as an "organisation dedicated to the heritage, identity, and future of people of European descent in the United States, and around the world".

Spencer was recently videotaped extending his right hand and shouting, "Hail Trump" at a conference in Washington DC. During a speech at Texas A&M University last week, the white nationalist said: "At the end of the day, America belongs to white men."

Last month, several high-profile accounts associated with the alt-right movement were suspended including those of Pax Dickinson, John Rivers, Ricky Vaughn and Paul Town. The Twitter accounts of The National Policy Institute and Spencer's online magazine, were also suspended.

The suspensions came the same day Twitter announced plans to upgrade some of its features to tackle harassment and hate speech on its site. Del Harvey, Twitter's head of safety, told USA Today that the upgrades were part of the social media giant's efforts to uphold freedom of speech whilst combating "behaviour that is intended to silence others".

Following the suspensions, Twitter told the publication in a statement: "The Twitter rules prohibit violent threats, harassment, hateful conduct and multiple account abuse, and we will take action on accounts violating those policies."

Twitter has now stated that Spencer's account was suspended for violating the "multiple account abuse" clause in their policies.

"Our rules explicitly prohibit creating multiple accounts with overlapping uses," a spokesperson told Mashable, "When we temporarily suspend multiple accounts for this violation, the account owner can designate one account for reinstatement."

Spencer quickly tweeted saying his account was back online, adding that he plans to try and get his other suspended accounts reinstated as well.

However, many Twitter users have voiced their outrage over his account's reinstatement, questioning the company's ability and efforts to tackle hate speech and accounts that violate its policies.

After Spencer's account was banned, he argued that the move was part of a "coordinated effort to just wipe out alt-right Twitter" in response to mounting criticism that social media helped Donald Trump win the White House.

He also said the suspensions were different from that of Milo Yiannopoulous. In July, the conservative tech editor of right-wing American news website Breitbart News was banned from the platform over accusations that he incited his followers to target Ghostbusters actress Leslie Jones with a barrage of vicious racist and sexist vitriol.

"I supported people like Milo when they were banned from Twitter, but Milo was engaging in something that could be called harassment," Spencer said in a YouTube video published in response to the suspension. "I and a number of other people who just got banned were not even trolling. I was using Twitter just like I always used Twitter: to give people some updates and maybe comment on a news story here and there."

"It is corporate Stalinism," he added. "There is a great purge going on, and they are purging people based on their views."

The Twitter accounts of the National Policy Institute, Radix Journal and Dickinson are still suspended.

Twitter user Liam Hogan noted that Twitter recently verified Matthew Heimbach, the head of the Traditionalist Worker Party (TWP) and Traditional Youth Network (TYN), who has been described by the Southern Poverty Law Center as "the face of a new generation of white nationalists."