German Vice Chancellor Sigmar Gabriel says Saudi Arabia must stop financing fundamentalist mosques abroad that are accused of breeding extremism.
"From Saudi Arabia, Wahhabi mosques are financed throughout the world," said Gabriel, referring to the austere version of Sunni Islam of 18th century preacher Sheikh Mohammed bin Abdul Wahhab, who co-founded the Saudi state.
"In Germany many Islamists considered dangerous persons emerge from these communities," he told the newspaper Bild am Sonntag.
Gabriel, who is Chancellor Angela Merkel's deputy in a left-right coalition, warned against alienating Saudi Arabia, a crucial player in the bid to end the Syrian war, with too much criticism.
"At the same time we must make it clear to the Saudis that the time of looking the other way is over," said Gabriel, who is also economy minister.
The preaching associated with Wahhabi thought, including a return to Islam as practised by the first generation of Muslims, has been accused of inspiring extremists from Osama bin Laden to the Islamic State group.
Gabriel, head of the centre-left Social Democrats (SPD), urged decisive steps in Germany against radical mosques associated with Islam's ultraconservative Salafist strand.
"This radical fundamentalism taking place in Salafist mosques is no less dangerous than right-wing extremism," he said.
The head of the SPD parliamentary group, Thomas Oppermann, also urged steps against preaching that contradicts the basic freedoms guaranteed in the German constitution.
"We will prevent Saudi help in the building or financing of mosques in Germany where Wahhabi ideas are to be disseminated," he told the Welt am Sonntag newspaper.
Wahhabism provided the "complete ideology of the Islamic State and contributes in other countries to a radicalisation of moderate Muslims," he said, adding that "this is something we don't need and don't want in Germany".