Germany on Wednesday banned Ansaar International, accusing it of collecting donations to help finance terrorism worldwide.
The prohibition came along with a series of raids on properties in ten states, with investigators also seizing items.
Interior Minister Horst Seehofer "has banned the association Ansaar International and its related organizations. The network finances terrorism worldwide with donations," tweeted ministry spokesman Steve Alter.
"If you want to fight terror you have to dry up its sources of funding," said Seehofer.
Ansaar says on its website it provides humanitarian aid to people affected by war and crises by, for instance, building or financing the construction of hospitals, orphanages and schools.
In 2018 alone, it collected 8 to 10 million euros in donations, according to its first chairman.
The interior ministry said however that the funds are in fact raised with the intention of financing foreign groups such as the Palestinian movement Hamas as well as the Al-Qaeda-linked Al-Shabaab and al-Nusra Front.
"Financial support, even for what at first glance appear to be charitable activities, secures the terrorist groups' power and dominance in the respective region, facilitates the recruitment of activists, and saves the terrorist group money, which in turn can be used to carry out the crimes it plans," said the ministry.