President Donald Trump has been party to an eye-watering 4,000 lawsuits over the last 30 years, US media say.

And now the mogul turned commander-in-chief has attracted one more, after seven people sued him for blocking them on Twitter.

Mr Trump is an avid user of the social media forum, which he deploys to praise allies and lambast critics.

The lawsuit was filed by the Knight First Amendment Institute, a free speech group at Columbia University.

The seven Twitter users involved claim their accounts were blocked by the president, or his aides, after they replied to his tweets with mocking or critical comments.

People on Twitter are unable to see or respond to tweets from accounts that block them.

The legal complaint argues that by blocking these individuals, Mr Trump has barred them from joining the online conversation.

It calls the move an attempt to "suppress dissent" in a public forum - and a violation of their First Amendment right to free speech.

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White House Press Secretary Sean Spicer and the president's social media director Daniel Scavino are also named in the lawsuit.

Last month, Mr Spicer said Mr Trump's tweets were considered "official statements by the president of the United States".

The president's @realDonaldTrump Twitter account has 33.7m followers, while the official @POTUS account has 19.3m.

Media captionTrump Twitter museum opens in New York

Jameel Jaffer, executive director of the Knight First Amendment Institute, said the president's love of Twitter means it has become "an important source of news and information about the government".

"The First Amendment applies to this digital forum in the same way it applies to town halls and open school board meetings," he said.

"The White House acts unlawfully when it excludes people from this forum simply because they've disagreed with the president."

According to the institute, the account's blocking habit should be a concern for everyone.

Why? Because even if they can read the president's tweets, what they see has been consciously cleansed of criticism.

President Trump's past lawsuits

• Mr Trump resolved three lawsuits over the now-defunct Trump University, which centred on former students claiming they were charged tens of thousands of dollars for courses that promised to unlock the secrets of entrepreneurship - but didn't. Mr Trump had always denied the claims, but settled for $25m (£20m).
• In 2006, he filed a $5bn lawsuit against author Timothy O'Brien and his publisher, saying they had understated his wealth. In his book Trump Nation, Mr O'Brien wrote that three people close to the property magnate had put his worth at between $150m and $250m. Mr Trump argued it was between $4bn and $6bn - and said the low valuation had damaged his reputation. A judge disagreed, and his suit was dismissed.

Media captionUS President Trump sued over business connections

• Republican political strategist Cheryl Jacobus filed a $4m libel lawsuit against the president-to-be in 2016, claiming he had "destroyed her career" by calling her "a dummy" on Twitter. The suit was thrown out by a New York judge, who ruled that the slur did not qualify as defamatory.