The most prominent German politician of Turkish origin said it would be difficult for the head of the national soccer association to stay in the role, adding that Ozil's departure would only be welcomed by those who opposed diversity.

Ozil's announcement on social media late on Sunday led national newspapers to clear their front pages for the midfielder, 29, a key member of Germany's World Cup-winning side in 2014 - and also of the side eliminated at the group stage of the 2018 tournament in Russia.

The player, who came under fire for having his photograph taken with Turkey's authoritarian President Tayyip Erdogan in May, was especially piqued by criticism from German Football Association (DFB) head Reinhard Grindel, who he said blamed him for Germany crashing out of this year's tournament.

A spokesman for the DFB did not respond immediately when asked for a comment from Grindel.

Cem Ozdemir, the former head of the Greens party and the most prominent politician of Turkish background, said it would be difficult for Grindel to do his job in future given the diverse reality of Germany and its soccer team.

"It will be very hard for Grindel after this," he told Deutschlandfunk radio. "He doesn't reflect the breadth of football in Germany and so it will be hard for German Turks, or indeed German Croats, to feel that the DFB is theirs."

Gokay Sofuoglu, leader of the Turkish community in Germany, called for Grindel to resign, adding: "Diversity in the national team was a great showcase project that is now at risk of failing due to incompetent leaders."

Former DFB President Theo Zwanziger was quoted in German media as saying the DFB had not done enough to solve conflicts ahead of the World Cup.

"Communication mistakes mean something happened that should never happen to migrants: They should never feel like second-class Germans," he said, adding: "Ozil's resignation is a major setback for integration efforts beyond football in our country."

The DFB said it regretted Ozil's departure but rejected his accusations of racism, saying it had for years helped to integrate people with migrant backgrounds and would continue to do so, adding: "The DFB stands for diversity".

A spokeswoman for Chancellor Angela Merkel said on Monday that most of the roughly three million people with Turkish roots living in Germany were well-integrated.

She said Germany was a "cosmopolitan country" where people with migrant backgrounds were welcome and sport played a big role in integration. Merkel valued Ozil as a "great" footballer.

CRITICISM AND PRAISE

The row coincides with a testy political debate in Germany about an influx of 1.6 million migrants since mid-2014 that has seen a rise of the far right Alternative for Germany (AfD) party at the expense of traditional parties.

It also exposed differences of opinion over the country's large and well-established Turkish community.

Hundreds of thousands of Turks came to Germany in the 1960s to help it tackle a shortage of labor as "guest workers" but little attempt was made to help them learn German and integrate.

A survey by the WZB Berlin Social Science Center in June showed people of Turkish descent, like other groups with migrant backgrounds, suffered discrimination when they applied for jobs.

Just as 2014's victorious German side was celebrated for its diversity, so too was France's World Cup-winning team in 2018 for having numerous key players with African ethnic roots.

German soccer star Jerome Boateng, born in Berlin with a Ghanaian father, tweeted a photo of himself with Ozil and wrote: "It was a pleasure Abi". "Abi" means brother in Turkish.

But German Foreign Minister Heiko Maas questioned the debate around Ozil, who plays for English club Arsenal, saying: "I don't believe the case of a multimillionaire living and working in England gives much insight into the success or failure of integration in Germany."

British anti-discriminatory body Kick It Out said the "racist treatment" Ozil had received at the hands of media, supporters and society was disappointing but reflected what a number of footballers with mixed heritage in Europe faced.

Ozdemir said that even if Ozil had been naive, however, his departure would be "good news for Erdogan, for the AfD, all those who are against diversity."

AfD leader Alice Weidel wrote that: "The integration dream doesn't work even with football millionaires," describing Ozil's "tirade" as a "typical example of failed integration".

In Turkey, however, politicians heaped praise on the player and lashed out at those who had abused him.

"What Mesut Ozil went through and how he was treated is unforgivable. There is NO excuse for racism and discrimination," Gulnur Aybet, a senior adviser to Erdogan wrote on Twitter.

Ozil's main sponsor, Adidas, said it would stand by him.