President Donald Trump has insisted that a wave of protests held by National Football League players during the US anthem before games had "nothing to do with race".

He escalated his feud with American football after players staged their biggest anti-racism protest yet at London's Wembley Stadium on Sunday.

The protest, which was followed by more demonstrations in America, came hours after Mr Trump called for a boycott of the NFL as he vented his fury on Twitter throughout the day.

In a direct challenge to Mr Trump, two dozen players from the Baltimore Ravens and Jacksonville Jaguars went down on bended knee as the US national anthem was played while others, including the Jaguars owner Shad Khan, who is a Muslim, stood and locked arms.