England midfielder Jordan Henderson said fans who booed players for taking a knee before matches proved racism is still an issue and that the team will continue taking a stand against it during the upcoming European Championship.

There were jeers from a small section of spectators at the Riverside Stadium in Middlesbrough when players took the knee before England's friendly wins over Austria and Romania last weekend.

"It shows that if there are still people booing because we're standing together against racism, then there still is a problem and we've still got to fight it and stand together," Henderson said before Sunday's opener against Croatia.

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"It shows even more that we have to keep going, keep fighting it. From our side, it's about being together and doing what we think is right."

In an open letter to fans on Wednesday, coach Gareth Southgate said his team will not "just stick to football" during the Euros and that it was his responsibility to put debates such as racial awareness in the spotlight.

Henderson said the Three Lions are determined to lead the fight against racism but their focus was on playing football. "Of course, everyone knows we stand together and you'll see that in taking the knee, but we want to get on with the football and concentrate on that," he said.

England, semifinalist at the 2018 World Cup, faces Scotland on June 18 and the Czech Republic four days later after playing Croatia, with all games being held at Wembley.

A similar incident took place in Hungary before Tuesday's 0-0 draw with Ireland. Ireland coach Stephen Kenny condemned the "incomprehensible" behaviour of Hungary fans who booed his players for taking a knee before the game in Budapest.

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While Ireland players took a knee, the Hungary team stood and pointed to its sleeves, which had European football governing body UEFA's 'respect' badge.

"The fact it was booed is incomprehensible really and it must be damaging for Hungary, with the Euros in Hungary," said Kenny.

Budapest is one of 11 host cities for the Euros, which begin on June 11.

"It's disappointing and it doesn't reflect well on Hungary really, on Hungarian support," he added.

The Hungarian Football Federation (MLSZ) said before the game its players would not take a knee "to express its condemnation of any form of hatred, but will instead find other ways".

"The Hungarian national team not only follows the international rules and norms in every case, but also respects everyone, be they an opponent, a fan or anyone else," the MLSZ said on its website.

"The rules of UEFA and FIFA do not allow politicisation on the pitch or in the stadium, values which the MLSZ not only accepts but also agrees with."