The owner of the Dallas Cowboys has said that his players will not be allowed to play if they refuse to stand for the national anthem.

Jerry Jones, who owns the NFL side, issued the order on Sunday, after US Vice President Mike Pence left a game as an act of protest against the players who took a knee during the national anthem prior to kick-off.

"If there is anything that is disrespectful to the flag then we will not play," Jones said.

Jones' decision comes just two weeks after he kneeled arm-in-arm with his players before the national anthem was played for their fixture against the Arizona Cardinals.

They then stood arm-in-arm for the anthem to show their solidarity for the ongoing league-wide protests.

NFL players and management across the country took a knee during the anthem that weekend after US President Donald Trump said players should be fired if they refuse to stand for the anthem.

He also referred to players participating in that protest as "sons of b******".

Jones appears to have changed his position on the matter and when asked about Pence's decision to leave the game, Jones said:

"I know this, we cannot ... in the NFL in any way give the implication that we tolerate disrespecting the flag. We know that there is a serious debate in this country about those issues, but there is no question in my mind that the National Football League and the Dallas Cowboys are going to stand up for the flag. So we're clear."

Trump has published a tweet in support of Jones' statement, and other teams have reportedly told their players to stand for the anthem in the future.

Former San Francisco 49ers quarterback Colin Kaepernick, who was the first to kneel during the anthem to protest against the treatment of black people in America.

He is no longer with the 49ers and is still waiting to be offered a new job. It was reported on Sunday night that he would be willing to stand if given a new job, but those reports were later revealed as false.