A German football club has released one of its players over links to an Islamic charity with alleged ties to extremism.

Bundesliga club Darmstadt let Tunisian midfielder Anis Ben-Hatira go on Wednesday after it emerged he had connections with Ansaar International. The NGO has been heavily criticised in German media over its links to the controversial Salafist sect of Islam.

Darmstadt president Ruediger Fritsch says the club "feels Ben-Hatira's private humanitarian assistance for the organisation, the one he is serving, is wrong".

"Further co-operation makes no sense," he added. "We wish Mr Ben-Hatira, who has always behaved impeccably, every success in his future sporting career."

The charity is described by the Office for the Protection of the Constitution in the state of North Rhine-Westphalia as "firmly interwoven in the German Salafist scene".

The ultra-conservative branch of Sunni Islam looks to bring Muslims back to its origins and the name stems from the Arabic phrase 'as-salaf as-saliheen', referring to Islam's first three generations of Muslims.

The interior minister of the state of Hessen, where the club is located, Peter Beuth, said: "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 the Federal Office for the Protection of the Constitution."

But Ben-Hatira remained defiant in the face of calls for him to distance himself from the organisation.

"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."