Hillary Clinton has said “it’s quite telling” that Donald Trump is “willing to attack black athletes” and not white supremacists, weighing in on the US President’s suggestion that players who take a knee during the national anthem should be fired.

“He attacks black athletes as he did starting with his rally in Alabama. Continued on Twitter. And he attacks them for protesting peacefully for equality, for standing up for what they believe,” Ms Clinton said in an interview with MSNBC’s Chris Hayes.

“And he does it once again to dog whistle to his base and to try to detract attention from other things that are going on,” she continued. “But it's quite telling that he is willing to attack black athletes. He never says anything of an insulting manner towards white supremacists or neo-Nazis or Ku Klux Klaners or Vladimir Putin, right?”

Mr Trump’s controversial comments in Alabama sparked a wave of football protests on Sunday, with many NFL players across the US and in London kneeling during the national anthem.

Colin Kaepernick, formerly a quarterback for the San Francisco 49ers, began the movement last year to highlight police brutality and racial injustice. About three-quarters of NFL players are black.

While Mr Trump has been quick to condemn such protests by athletes, he was criticised last month for his delay in equivocally denouncing members of the Ku Klux Klan and neo-Nazis after violence broke out following a white nationalist rally in Charlottesville, Virginia.

The President proceeded to claim that there were “bad” people on both sides in Charlottesville – including the white nationalists and protesters who opposed them – raising new questions as to how his administration will be viewed over race relations.

Violence on the streets of Charlottesville Show all 9 1 /9 Violence on the streets of Charlottesville Violence on the streets of Charlottesville Protesters clash and several are injured White nationalist demonstrators clash with counter demonstrators at the entrance to Lee Park in Charlottesville, Virginia. A state of emergency is declared, August 12 2017 Violence on the streets of Charlottesville Trump supporters at the protest A white nationalist demonstrator walks into Lee Park in Charlottesville, Va., Saturday, Aug. 12, 2017. Hundreds of people chanted, threw punches, hurled water bottles and unleashed chemical sprays on each other Saturday after violence erupted at a white nationalist rally in Virginia. AP Photo Violence on the streets of Charlottesville State police stand ready in riot gear Virginia State Police cordon off an area around the site where a car ran into a group of protesters after a white nationalist rally in Charlottesville, Virginia AP Photo Violence on the streets of Charlottesville Militia armed with assault rifles White nationalists, neo-Nazis and members of the 'alt-right' with body armor and combat weapons evacuate comrades who were pepper sprayed after the 'Unite the Right' rally was declared a unlawful gathering by Virginia State Police. Militia members marched through the city earlier in the day, armed with assault rifles. Getty Images Violence on the streets of Charlottesville Statue of Confederate General Robert E Lee The statue of Confederate General Robert E. Lee stands behind a crowd of hundreds of white nationalists, neo-Nazis and members of the 'alt-right' during the 'Unite the Right' rally 12 August 2017 in Charlottesville, Virginia. They are protesting the removal of the statue from Emancipation Park in the city. Getty Images Violence on the streets of Charlottesville Racial tensions sparked the violence White nationalists, neo-Nazis and members of the 'alt-right' exchange insults with counter-protesters as they attempt to guard the entrance to Lee Park during the 'Unite the Right' rally Getty Violence on the streets of Charlottesville A car plows through protesters A vehicle drives into a group of protesters demonstrating against a white nationalist rally in Charlottesville, Virginia. The incident resulted in multiple injuries, some life-threatening, and one death. AP Photo Violence on the streets of Charlottesville Rescue personnel help injured people after a car ran into a large group of protesters after an white nationalist rally in Charlottesville, Virginia AP Photo Violence on the streets of Charlottesville President Donald Trump speaks about the ongoing situation in Charlottesville, Virginia from his golf club in Bedminster, New Jersey. He spoke about "loyalty" and "healing wounds" left by decades of racism.

During a press gaggle following several of the NFL players’ demonstrations on Sunday, Mr Trump said kneeling during the anthem was “disrespectful to our flag and to our country”, adding that team owners “should do something about it.”

“We have great people representing our country, especially our soldiers, our first responders, and they should be treated with respect,” Mr Trump said. “And when you get on your knee and you don't respect the American flag or the anthem, that's not being treated with respect.”

Mr Trump said comments had “nothing to do with race”.

“I've never said anything about race,” Mr Trump said, responding to a question about whether he was inflaming racial tensions. “This has nothing to do with race or anything else. This has to do with respect for our country, and respect for our flag.”

On Tuesday, Mr Trump continued to comment on the players' protests, suggesting that the NFL's TV ratings are down, “except before game starts, when people tune in to see whether or not our country will be disrespected!”