Bundesliga club Darmstadt have released Tunisian midfielder Anis Ben-Hatira by mutual consent following criticism of his ties with an Islamic charity.
Ansaar International has been criticised in Germany with media reports alleging it was linked to the controversial Islamic Salafist sect.
Salafism is an ultra-conservative branch of Islam.
German authorities say "almost all"terror networks in the country have evolved out of the movement.
However, there is an important distinction to be made between the vast majority of its followers, whose aim is simply to bring Muslims back to an earlier interpretation of their religion.
German politicians have also spoken against Ansaar International.
Peter Beuth, interior minister of the state of Hessen, where Darmstadt is located, said on Tuesday: "You cannot let a professional footballer like Ben-Hatira carry on when he's in the vicinity of extremist organisations that are being observed by [Germany's domestic security agency] the Federal Office for the Protection of the Constitution."
Darmstadt's president said the club felt Ben-Hatira's involvement with the organisation was "wrong".
"Further co-operation makes no sense," Rudiger Fritsch added. "We wish Mr Ben-Hatira, who has always behaved impeccably, every success in his future sporting career."
On Saturday, Darmstadt fans unfurled a banner calling on Ben-Hatira to distance himself from Ansaar International.
The Berlin-born player responded the next day on Facebook, describing the fans' actions as a "smear campaign".
Ben-Hatira defended his work with Ansaar, who have projects in Syria, Somalia, the Palestinian territories and Afghanistan.
"Anyone who looks at my CV will quickly see that I am socially involved and fight for equal treatment between people of different skin colour, ethnicity or faith," he wrote.
He added: "Are you not ashamed? Do you really think I'll let myself be intimidated by that?
"I think the real scandal is that there is now an attempt to sabotage my sports career in Germany."
