DAVOS, Switzerland - US President Donald Trump drew boos from the audience at the elite Davos summit Friday when he attacked the press, repeating his charge that critical media indulge in “fake” news.

The calm atmosphere established by a brass band at the start of his appearance, and Trump’s measured tone during his speech, gave way to a flash of tetchiness afterwards. Trump went off-script in a brief question-and-answer exchange with World Economic Forum host Klaus Schwab.

“As a businessman I was always treated really well by the press... it wasn’t until I became a politician that I realised how nasty, how mean, how vicious and how fake the press can be,” Trump said. Some of the 1,500 delegates in the packed conference hall booed at those remarks. The official White House transcript of Trump’s speech recorded the reaction to his remarks on the media merely as “laughter”.

 Donald Trump said Friday that US-backed coalition forces had won back almost 100 percent of territory occupied by the Islamic State group in Iraq and Syria.

“The coalition to defeat ISIS (IS) has retaken almost 100 percent of the territory once held by these killers in Iraq and Syria,” Trump said in a speech at the World Economic Forum in Davos, Switzerland.

“There is still more fighting and work to be done and to consolidate our gains.”

IS has been dealt a string of defeats across Iraq and Syria in recent months. The US-led coalition said on Tuesday it had killed as many as 150 IS fighters in an operation in the middle Euphrates River Valley in Syria, where some remained entrenched.

It said the Syrian Democratic Forces, a US-backed Arab-Kurdish alliance fighting IS, had assisted in target observation prior to the strike.

Kurdish ground forces have played a critical role in defeating IS. On Wednesday IS claimed responsibility for a deadly attack on Save the Children’s office in east Afghanistan that left at least two people dead and 14 others wounded.

“We are committed to ensuring that Afghanistan never again becomes a safe haven for terrorists who want to commit mass murder to our civilian populations,” Trump added in his speech.

Meanwhile, President Donald Trump’s administration has unveiled a sweeping new immigration plan to Congress that offers 1.8 million young unauthorized immigrants known as “Dreamers” a path to citizenship over 10-12 years.

In a comprehensive reform that will be formally presented next week, Trump also asked Congress Thursday to eliminate the popular “green card lottery” program and severely restrict family immigration, steps analysts say could cut in half the more than one million foreign-born people moving to the country annually.

And in the name of halting illegal immigration, he has also demanded Congress budget $25 billion for a “trust fund” for constructing a wall on the US-Mexico border - a major plank of Trump’s White House campaign.

Moreover, the president on Friday dismissed as “fake news” bombshell reports that he had ordered the firing of Russia investigation special prosecutor Robert Mueller last year, only backing off in the face of a threatened resignation.

“Fake news. Fake news. Typical New York Times. Fake stories,” Trump told reporters as he arrived for meetings at the World Economic Forum summit in Davos, Switzerland.

The New York Times and other US media reported Thursday that Trump had ordered the firing of Mueller in June 2017 but that the president climbed down when the top White House lawyer threatened to resign.

Mueller is leading the probe into allegations of collusion between the US president’s campaign team and Russia in the 2016 election.

Trump has repeatedly criticized the probe which he says is an attack on the legitimacy of his presidency.

The New York Times said White House counsel Don McGahn opposed the firing decision, telling senior officials it would have a “catastrophic effect” on Trump’s presidency.

After McGahn threatened to quit, Trump changed his mind, the Times reported, citing four anonymous sources.

The Washington Post, also citing anonymous sources, confirmed that Trump sought to fire Mueller but reconsidered after the White House counsel’s threat.

Trump attorney Ty Cobb told AFP: “We decline to comment out of respect for the Office of the Special Counsel and its process.”

But Trump had no such scruples about commenting as he arrived at a conference center in the snowbound Swiss mountain resort on Friday.

The president had told journalists in August that he had not considered firing Mueller, some two months after he reportedly had moved to do just that.

“I haven’t given it any thought. I mean, I’ve been reading about it from you people, you say, ‘Oh, I’m gonna dismiss him.’ No, I’m not dismissing anybody,” Trump said.

According to the Times, Trump had accused Mueller of three conflicts of interest that he argued disqualified him from running the Russia collusion investigation.

They were as follows: Mueller had terminated his membership at a Trump golf course over a dispute about fees, had worked for the law firm that previously represented the president’s son-in-law Jared Kushner, and had been interviewed to return as FBI director before he was appointed special counsel.

Democratic Senator Mark Warner, the vice chair of the Senate Select Committee on Intelligence, said Thursday that firing Mueller would be a “red line.”

“I’ve said it before, and I am saying it again: firing the special counsel is a red line that the president cannot cross,” Warner said in a statement.

“Any attempt to remove the special counsel, pardon key witnesses, or otherwise interfere in the investigation, would be a gross abuse of power.”

The day before, Trump for the first time directly said that he would cooperate with Mueller, whose investigation he had previously dismissed as a “witch hunt.”

“I would love to do it,” Trump told reporters in the White House when asked about testifying.

“I would do it under oath, absolutely.”

Any interview of a US president in an investigation is fraught with issues of executive privilege - how much and in what context the US leader can be forced to disclose information.

In Trump’s case, it also raises deep concerns that his shoot-from-the-hip outspokenness could jeopardize his own legal position.