Colin Kaepernick continues anthem protest in San Diego

New England Patriots - Atlanta Falcons Live

San Francisco 49ers quarterback Colin Kaepernick knelt with his arms folded during the performance of the U.S. national anthem during a pre-season game in San Diego on Thursday, continuing his protest against racial injustice and police brutality.

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Kaepernick, 28, had pledged to continue sitting during the performance of "The Star-Spangled Banner" before National Football League games, a move that has been both criticized and cheered by commentators.

Crowd reaction

He was met by heavy boos from the crowd during pre-game warm-ups and during his first offensive drive at Qualcomm Stadium in San Diego, which is home to many US Navy and Marine bases.

"A lot of issues in this country"

"We have a lot of issues in this country that we need to deal with," he said after the game. "We have a lot of people that are oppressed. We have a lot of people that aren't treated equally, aren't given equal opportunities."

The game coincided with "Salute the Military Night," which saw 240 sailors, Marines and soldiers present a US flag and a pre-game parachute jump by retired Navy SEALS.

"Not aimed at the military"

Kaepernick has said his protest is not aimed at the military, but some view his refusal to stand for the anthem as disrespectful to the armed forces. Kaepernick applauded from the sidelines during a second-quarter salute to military members.

One of his teammates, safety Eric Reid, knelt alongside the quarterback during the singing. Seattle Seahawks cornerback Jeremy Lane also sat during the playing of the national anthem before his pre-season game in Oakland, media have reported, although his motivation was not clear.

Kaepernick, who led San Francisco to the 2013 Super Bowl but has since been demoted to backup, has said he would not show pride in the flag of a country that oppresses people of colour, citing police brutality.