US president Donald Trump has once again spoken out on the row over NFL anthem protests – suggesting players who kneel during The Star Spangled Banner should be suspended or not paid.

The debate over the protests, which has been ongoing for months, was ignited again this week when it was reported that the Miami Dolphins had formally told players they could be punished for protesting on the field.

Writing on Twitter, Trump expressed surprise that the debate was “alive and well again” – and proposed a two-pronged penalty for protesters.

He said: “The NFL National Anthem Debate is alive and well again – can’t believe it! Isn’t it in contract that players must stand at attention, hand on heart? The 40,000,000 dollar (£30m) Commissioner must now make a stand. First time kneeling, out for game. Second time kneeling, out for season/no pay!”

Trump previously suggested anthem protesters “shouldn’t be in the country”, and has also called for NFL owners to sack players who refused to stand.

In May, NFL owners announced that players must respect the anthem by standing, or otherwise stay off the field in the dressing room.

A decision was also made to fine teams whose players do not stand.

Kneeling during the anthem began in 2016 when then San Francisco 49ers quarterback Colin Kaepernick did so to protest against police brutality towards African-Americans.

The 2017 season was marked by numerous protests during the pre-game anthems, with several players taking a knee to raise awareness of social and racial inequality.