Germany on Wednesday banned the Hamburg Islamic Centre, an association that has been under investigation for several months over its alleged support for Lebanon's Hezbollah group and its links to Iran.
Tehran reacted in fury, summoning Germany's ambassador to Iran to condemn Berlin's "hostile action" which it branded as a "clear example of Islamophobia".
Germany's Interior Ministry accused the centre of presenting itself as a purely religious organisation with no political agenda, but said its probe has found the contrary to be true.
In a statement, the ministry said that it "banned the Hamburg Islamic Centre and its affiliated organisations throughout Germany to date, as it is an Islamist extremist organisation pursuing anti-constitutional objectives".
Accusing the group of being a "direct representative of Iran's supreme leader", the ministry said the centre spreads Tehran's ideology "in an aggressive and militant manner".
It is allegedly seeking to "establish authoritarian, theocratic rule" in place of a democracy, said the ministry, accusing the centre of backing the "military and political dimension" of organisations like Hezbollah.
It is also believed to propagate anti-Semitism, something that Germany has been battling to stem amid a jump in cases following Israel's war in Gaza, launched in response to a deadly attack by Hamas militants on Israeli soil.
Investigators raided 53 properties allegedly linked to the centre across Germany on Wednesday, and the ban will also be imposed on several organisations related to the Hamburg centre -- including four Shiite mosques.
"I want to make it very clear: We are not taking action against a religion," said Interior Minister Nancy Faeser.
"We are drawing a clear distinction between the Islamist extremists that we are cracking down on and the many Muslims who belong to our country and live according to their faith.
"This ban absolutely does not apply to the peaceful practice of the Shiite religion," she stressed.
Germany considers Hezbollah a "Shiite terrorist organisation" and in 2020 banned Hezbollah from carrying out activities on its soil.
The Hamburg Islamic Centre runs the Imam Ali Mosque, also known as the Blue Mosque, and calls have grown in recent years for authorities to close it down because of its alleged links to Iran.
Blasting Berlin over its decision, Iran's foreign ministry said "what happened in Germany today is a clear example of Islamophobia and a confrontation to the teachings of the Abrahamic religions".
The ministry hailed "valuable and unforgettable services of Islamic centres, including the Hamburg Islamic Centre, in explaining the religious teachings of Islam, promoting the principle of dialogue and religious tolerance, as well as combating extremism."
Founded by Iranian immigrants in 1953, the Hamburg Islamic Centre had already been under surveillance by domestic intelligence for some time.
In November, investigators had conducted sweeping raids of its premises and other related sites across seven of Germany's 16 states.
"Extensive evidence" that was secured then had "confirmed suspicions sufficiently to order today's ban" of the group, said the interior ministry.
The regional government of Hamburg welcomed the decision, with interior minister of the state Andy Grote saying the "closure of this outpost of the Iranian inhumane regime is a real blow against Islamist extremism".