U.S. President Donald Trump's Twitter election campaign account was unblocked on Thursday after the social media site temporarily restricted it, saying a video posted by the account about Democratic presidential candidate Joe Biden's son violated its rules.

The video posted by the @TeamTrump account referred to a New York Post story from Wednesday that contained alleged details of Hunter Biden's business dealings with a Ukrainian energy company and said the former vice-president had met with an adviser of the company.

The Trump campaign, with 2.2 million followers, said in a new tweet it was "re-posting the video Twitter doesn't want you to watch." Twitter did not respond to a request for a comment about why the account had been unblocked.

"Joe Biden is a liar who has been ripping off our country for years," the video was captioned.

Twitter said earlier the video violated its rules against posting private information, adding the account may need to delete the post in order to continue tweeting.

Trump threatens lawsuit

"It's going to all end up in a big lawsuit and there are things that can happen that are very severe that I'd rather not see happen, but it's probably going to have to," Trump said, when asked about the move by Twitter.

Twitter said on Wednesday the Post story violated its "hacked materials" policy, which bars the distribution of content obtained through hacking that contains private information or trade secrets, or puts people at risk of physical harm.

Facebook and Twitter took proactive steps on Wednesday to restrict dissemination of the Post story in the hours after it was published.

Twitter had placed similar restrictions on the account of White House Press Secretary Kayleigh McEnany on Wednesday, after she shared the Post story.

Other Twitter users, including a journalist, said their accounts had been suspended because they had posted a link to the New York Post story. The accounts were unblocked after they deleted the offending tweets.

After Twitter imposed the restrictions, the U.S. Senate judiciary committee moved to subpoena Twitter's Chief Executive Jack Dorsey.

Committee Chair Lindsey Graham and Republican senators Ted Cruz and Josh Hawley said the committee will vote on sending the subpoena on Tuesday, Oct. 20, and plans to have Dorsey in front of the committee by Oct. 23.

Dorsey said on Twitter Wednesday that "our communication around our actions on the @nypost article was not great. And blocking URL sharing via tweet or DM with zero context as to why we're blocking: unacceptable."