Germany manager Joachim Low was unhappy with home fans who booed midfielder Ilkay Gundogan during Friday's friendly in Leverkusen and questioned the reasoning behind their actions after the match.

"First of all, having a national player booed like that helps nobody. I ask you this -- what should Ilkay do now?" Low said after Germany's 2-1 victory over Saudi Arabia in their final World Cup warmup.

Gundogan and Germany teammate Mesut Ozil drew criticism from politicians and Reinhard Grindel, the head of the Germany football federation (DFB), for having their photographs taken with Turkish president Recep Tayyip Erdogan last month.

Manchester City's Gundogan and Arsenal's Ozil -- both born in the German city of Gelsenkirchen but of Turkish descent -- posed for photos during Erdogan's visit to London.

Gundogan and Ozil, who met German chancellor Angela Merkel during her visit to Germany's pre-World Cup training camp in Italy, were whistled by sections of the travelling support during the friendly defeat in Austria last weekend.

AP Photo/Martin Meissner

And Gundogan was roundly booed by large swaths of German fans on Friday after coming on as a substitute against the Saudis.

"He took a picture, yes, but he made no political statement," Low said.

"He spoke about this with the press last week and underlined his support for German values, that he was born here, brought up here, his family and friends are here. Everybody must move on from this now."

Ozil, who is nursing a minor knee issue, did not play in the match.

The incident also comes just a day after Germany team manager Oliver Bierhoff had urged supporters to back the players against Saudi Arabia in a call for unity among the team and fans.

"For all the irritation we have now, we are one team, also in Germany with our fans," Bierhoff told reporters. "Sure, things took the wrong direction a bit. But we are now looking ahead.

"And that's why I hope that everyone, even though maybe still annoyed, withholds their anger a bit."

Germany will begin their World Cup campaign against Mexico on June 17 in Moscow.