Basketball superstar LeBron James has called US President Donald Trump "a bum" and said he was "trying to divide" Americans as a row over a White House invite for NBA champions the Golden State Warriors escalated.

The United States president has followed up his scathing comments about protesting NFL players by withdrawing an invitation to the Warriors to attend the White House.

Trump on Friday attacked the NFL players who protest during the American anthem, insisting their owners should "fire" them - a stance the league has now described as "divisive" and "unfortunate".

Various players across the league have taken a stand by kneeling or raising their fist during The Star-Spangled Banner since the start of last season, including high-profile figures like Colin Kaepernick, Michael Bennett and Marshawn Lynch.

Trump's comments at a rally in Alabama came on the same day Warriors point guard Stephen Curry, a two-time MVP and one of the most recognisable players in basketball, spoke about his dilemma over a possible Washington visit for his side.

It is commonplace in American sport for winners of competitions such as the NBA, MLB and NFL to be invited to meet with the president at the White House.

Two years ago Curry and his team-mates did so with Barack Obama, the former president whose final visitors were the Cleveland Cavaliers last November.

But even though it was reported no official invite had been extended to the Warriors, Curry made his position clear on Friday.

Speaking at the Warriors' pre-season media day, he said: "I don't want to go. (It would show) that we don't stand for what our president has ... the things that he's said and the things that he hasn't said in the right times, that we won't stand for it.

"By acting and not going, hopefully that will inspire some change when it comes to what we tolerate in this country and what is accepted and what we turn a blind eye to.

"It's not just the act of not going there. There are things you have to do on the back end to actually push that message into motion."

Curry later told ESPN: "We have an opportunity to send a statement that hopefully encourages unity, encourages us to appreciate what it means to be American and stand for something ... we want to take advantage of this opportunity (by not going)."

Trump took the decision out of Golden State's hands, tweeting: "Going to the White House is considered a great honor for a championship team.Stephen Curry is hesitating,therefore invitation is withdrawn!"

The NBA's most prominent player, LeBron James, reacted by writing on Twitter: "U bum @StephenCurry30 already said he ain't going! So therefore ain't no invite. Going to White House was a great honor until you showed up!"

James later tweeted a video saying sport brings Americans together and that he was frustrated because "this guy has tried to divide us again".

And the Warriors responded with an official statement on Saturday night which read: "While we intended to meet as a team at the first opportunity we had this morning to collaboratively discuss a potential visit to the White House, we accept that President Trump has made it clear that we are not invited.

"We believe there is nothing more American than our citizens having the right to express themselves freely on matters important to them. We're disappointed that we did not have an opportunity during this process to share our views or have open dialogue on issues impacting our communities that we felt would be important to raise.

"In lieu of a visit to the White House, we have decided that we'll constructively use our trip to the nation's capital in February to celebrate equality, diversity and inclusion - the values that we embrace as an organisation."

Earlier in the day, Trump drew criticism for his comments about the anthem protests in the NFL.

Kaepernick, who remains unemployed despite leading a team to the Super Bowl at the end of the 2012 season, was the first to protest over perceived racial injustice and police brutality. Bennett admitted the scenes at a white supremacist rally in Charlottesville, Virginia, about which Trump said there was "blame on both sides", partially motivated his own decision.

Trump said: "Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a b**ch off the field right now. Out. He's fired. He's fired'. Wouldn't you love it?"

A statement in response from NFL commissioner Roger Goodell on Saturday read: "The NFL and our players are at our best when we help create a sense of unity in our country and our culture.

"Divisive comments like these demonstrate an unfortunate lack of respect for the NFL and all of our players, and a failure to understand the overwhelming force for good our clubs and players represent in our communities."