More than 300 news outlets have launched a campaign to counter US President Donald Trump's attacks and promote a free press.

The Boston Globe made the call last week for a nationwide denouncement of the president's "dirty war" against the media, using the hashtag #EnemyOfNone.

Mr Trump has derided media reports as "fake news" and attacked journalists as "enemies of the people".

And he tweeted on Thursday: "The fake news media is the opposition party."

"It is very bad for our great country... But we are winning!"

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

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.

The initial positive response from 100 news organisations has grown closer to 350 with major US national newspapers and smaller local outlets answering the call, along with international publications like the UK newspaper The Guardian.

What have the papers said?
Starting with the Boston Globe itself, the editorial there, headlined Journalists Are Not The Enemy, argued that a free press had been a core American principle for more than 200 years

The New York Times chose the headline A Free Press Needs You, calling Mr Trump's attacks "dangerous to the lifeblood of democracy". It published excerpts from dozens more publications beneath

The New York Post - a pro-Trump tabloid - answered the Globe's call by saying "Who are we to disagree?" adding: "It may be frustrating to argue that just because we print inconvenient truths doesn't mean that we're fake news, but being a journalist isn't a popularity contest. All we can do is to keep reporting." But it also said: "Will this make a difference? Not one whit"

The Topeka Capital-Journal was another paper to join the campaign. It said of Mr Trump's attack on the media: "It's sinister. It's destructive. And it must end now." The paper was one of the few to endorse Mr Trump in 2016.

The fact that Mr Trump won without such media endorsements may cast doubt on whether the Globe's campaign would actually dent his support.

Later on Thursday, President Trump tweeted that the Globe "is in collusion with other papers on free press".

There have been some dissenting voices to the Globe's campaign:

At the conservative website Townhall.com, Tom Tradup panned the Globe's "pathetic bid to pretend it is still relevant", writing: "I would not presume to tell anyone else what to think or what to do. But as for me - and I suspect many others - I won't be putting any coins in any newspaper box August 16th."

The Wall Street Journal declined to take part. An earlier piece by James Freeman argued Mr Trump was entitled to free speech, and the Globe's drive ran counter to the very independence it was seeking.