China's under-20 team left the pitch for 25 minutes in the first of their series of matches against German fourth-division clubs after a Tibet flag was displayed by a section of 400 fans in attendance in Mainz.
China's U20 side are playing a series of friendlies against 16 teams from the regional southwest division to prepare for the 2020 Olympics.
The idea prompted controversy in Germany, and three fourth division clubs -- Waldhof Mannheim, TuS Koblenz and Stuttgarter Kickers -- rejected the chance to participate in the series. Those teams playing against China receive a €15,000 bonus.
On Saturday, around 400 fans attended China U20's debut at TSV Schott and witnessed a 25-minute break during the first half as the visiting players left the pitch when a Tibet flag was displayed by a group attending the match -- in reference to the push for Tibetan independence from China.
The game only resumed after the flags were no longer on display in the stands of TSV Schott's stadium.
"We wanted to be good hosts, and thus we are not pleased with the incidents," German Football Association (DFB) vice president Ronny Zimmermann said in a statement after the match.
He added that the DFB informed China's U20 side in the build-up "that the games will take place within the framework of the freedom of speech" and that "we are of the opinion that displaying a flag is part of it."
However, Zimmermann also condemned the incident, saying "football should not be misused for deliberate provocation of our guests."