German authorities have carried out raids on groups suspected of helping the militant Palestinian group Hamas under the guise of providing humanitarian aid.

The interior ministry said some 90 properties across Germany associated with an "Islamist network" were searched on Wednesday. It said the network was headed by two groups based in the western state of North Rhine-Westphalia, WWR Help and Ansaar International.

The ministry said there are indications that the network provided financial and propaganda support to Hamas, a longtime enemy of Israel that runs the Gaza Strip and was listed as a terror group by the European Union in 2001.

Interior Minister Horst Seehofer said that "anyone who supports Hamas under the cover of humanitarian aid flouts fundamental value judgments of our constitution."