Oakland Athletics catcher Bruce Maxwell has revealed he was refused service in a restaurant following his decision to kneel during the US national anthem.

Maxwell became the first Major League Baseball athlete to take a knee during The Star-Spangled Banner last month in a gesture of solidarity with NFL players protesting racial injustice.

A wave of protests erupted across the NFL and spread to other sports after kneeling players were condemned as "sons of bitches" by US President Donald Trump.

Maxwell told the TMZ.com website that a waiter who recognised him at a restaurant in Alabama refused to serve him following his protest.

"He denied us service at lunch and they had to go get us another waiter to wait on our table in that same restaurant," Maxwell said.

"He was like, 'You the guy who took the knee? I voted for Trump and I stand for everything he stands for.'"

Maxwell told TMZ the experience was all too common.

"That's where I'm from," Maxwell said. "And like I said, unless you're subject to it, you won't understand it, you won't feel it.

"I'm 26 years old. I'm very respectful. I'm very educated. And it still happens to this day. That's why I'm kneeling — stuff like that."

The NFL protests were launched last year by former San Francisco 49ers quarterback Colin Kaepernick.

Kaepernick began kneeling during the anthem to draw attention to racial injustice following the deaths of several black men during confrontations with law enforcement.

Source: AFP