Image copyright CBS Image caption Mr Chain was arrested in his California home by a Swat team on Thursday

The FBI has charged a man accused of making threatening calls to a newspaper that criticised President Donald Trump's attacks on the media.

The FBI says Robert Chain, 68, called the Boston Globe about a dozen times and threatened to shoot reporters.

He allegedly called journalists the "enemy of the people", using a phrase which has been frequently invoked by Mr Trump, who last tweeted it on Thursday.

Mr Chain was arrested on Thursday at his home in Encino, California.

Police say Mr Chain owned several firearms, and had recently purchased a small-calibre rifle.

If found guilty, Mr Chain could receive a sentence of up to five years in prison, and a $250,000 (£192,000) fine.

According to federal documents, Mr Chain first called the paper's newsroom on 10 August after the Globe called upon media outlets to denounce Mr Trump's "dirty war" on the press.

Media playback is unsupported on your device Media caption Fox v MSNBC: How the news divides America

The Boston Globe had pledged to write an editorial "on the dangers of the administration's assault on the press" on 16 August, and asked others to do the same.

Mr Trump frequently attacks "the fake news media" as the "opposition party", and repeated his "enemy of the people" line on Thursday:

Skip Twitter post by @realDonaldTrump I just cannot state strongly enough how totally dishonest much of the Media is. Truth doesn’t matter to them, they only have their hatred & agenda. This includes fake books, which come out about me all the time, always anonymous sources, and are pure fiction. Enemy of the People! — Donald J. Trump (@realDonaldTrump) August 30, 2018 Report

UN experts have warned that Mr Trump's comments about the media raise the risk of violence against journalists.

On 16 August, when nearly 350 newspaper answered the Globe's call and published editorials denouncing Mr Trump's attacks on the free press, Mr Chain allegedly called the paper again, this time to say he would shoot employees in the head, "later today, at four o'clock," according to court documents.

The threat resulted in a police presence outside the newsroom, in order to ensure employees' safety.

Mr Chain allegedly continued to harass the paper's staff, and on 22 August explained his reason for calling.

"Because you are the enemy of the people, and I want you to go [expletive] yourself," he is alleged to have said.

"As long as you keep attacking the president, the duly elected president of the United States, in the continuation of your treasonous and seditious acts, I will continue to threats, harass and annoy the Boston Globe."

He also incorrectly stated that the Boston Globe was owned by the the New York Times, which sold the paper in 2013.

Image copyright EPA Image caption The Boston Globe was targeted for their criticism of Mr Trump, the FBI says

The Boston Globe said in a statement it was grateful to law enforcement for taking the threat seriously.

"We couldn't have asked for a stronger response," said a representative for the paper.

"While it was unsettling for many of our staffers to be threatened in such a way, nobody - really, nobody - let it get in the way of the important work of this institution."

Harold Shaw, the FBI's special agent in charge of the Boston Division, said the arrest "should serve a warning to others, that making threats is not a prank, it's a federal crime".

"All threats are taken seriously, as we never know if the subject behind the threat intends to follow through with their actions.

"Whether potentially hoax or not, each and every threat will be aggressively run to ground."