Oct 15 (Reuters) - U.S. President Donald Trump's re-election campaign's Twitter account was briefly restricted from tweeting on Thursday, spurring an outcry from Republican lawmakers who accused social media companies of acting like "speech police" and vowing to hold Twitter responsible.

Twitter temporarily blocked the @TeamTrump account from sending tweets after it posted a video about Democratic presidential candidate Joe Biden's son that it said violated its rules.

The video 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.

A Twitter spokesman told Reuters earlier on Thursday that the @TeamTrump account, as well as the accounts of White House Press Secretary Kayleigh McEnany and the New York Post, had been blocked from tweeting due to the company's policies on hacked materials and posting private information. He said the accounts may need to delete the rule-breaking posts to continue tweeting.

The Trump campaign, with 2.2 million followers, was sending tweets again on Thursday afternoon. It said in a new tweet it was "re-posting the video Twitter doesn’t want you to watch." A Twitter spokesman told Reuters that the site would not take action as alterations to the video meant it no longer violated its policies.

Biden campaign spokesman Andrew Bates said in a statement that Republican-led Senate committees have previously concluded that Joe Biden engaged in no wrongdoing related to Ukraine.

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

"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 reduced how often the story shows up in users' news feeds and elsewhere on the Facebook platform, an action that spokesman Andy Stone said the company takes "if we have signals that a piece of content is false."

Twitter prohibited its users from posting links to the Post story, but its Chief Executive Jack Dorsey tweeted on Wednesday saying "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."

A Twitter spokesman declined to answer Reuters questions on whether Dorsey had been involved in the decisions on these restrictions on Wednesday or Thursday.

Neither the @nypost or @kayleighmcenany accounts have tweeted in nearly a day, suggesting that they are still blocked from posting.

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.

SENDING SUBPOENAS

Republican lawmakers slammed the social media companies' actions on Thursday. U.S. Senate majority leader Mitch McConnell said the blocking of the story was "reprehensible" and that there should be no "speech police" in the United States.

After Twitter imposed the restrictions, the U.S. Senate Judiciary Committee moved to subpoena Dorsey.

Committee Chairman 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.

Senator Hawley also called for sending a subpoena to Facebook.

"We're going to finally have an accounting that is long overdue," Graham said. "This to me crystallizes the problem better than anything I could think of."

The CEOs of Twitter, Facebook and Alphabet Inc's Google are also set to appear before the Senate Commerce Committee later this month at a hearing to discuss Section 230 - a prized legal immunity enjoyed by internet companies, which offers tech companies protection from liability over content posted by users.

The calls to reform Section 230 and penalize tech companies has been intensifying but there is little chance of action on the law by Congress this year.