Qatar has previously denied that it supports Islamist insurgents in Syria and Iraq
German Development Minister Gerd Mueller accused Qatar on Wednesday of financing Islamic State militants who have seized wide areas of northern Iraq and have posted a video of a captive American journalist being beheaded.
"This kind of conflict, this kind of a crisis always has a history ... The ISIS troops, the weapons - these are lost sons, with some of them from Iraq," Mueller told German public broadcaster ZDF.
"You have to ask who is arming, who is financing ISIS troops. The keyword there is Qatar - and how do we deal with these people and states politically?" said Mueller, a member of the Christian Social Union (CSU), the centre-right Bavarian sister party of Angela Merkel's Christian Democrats.
Mueller did not elaborate and presented no evidence of a Qatari link to Islamic State. A German government spokesman said he was checking whether Mueller's remarks reflected the official view of Berlin.
Officials at the Foreign Ministry of Qatar, a wealthy Gulf Arab state, did not immediately respond to requests for comment on his accusation.
Qatar has denied that it supports Islamist insurgents in Syria and Iraq. Diplomats and opposition sources say that while Qatar supports relatively moderate rebels also backed by Saudi Arabia and the West, it also has backed more hardline factions seeking to set up a strict Islamic state.
In March, David Cohen, the US Treasury Under Secretary for Terrorism and Financial Intelligence, cited reports of Qatari backing for Islamist fighters in Syria and described this as a "permissive jurisdiction" for donors funding militants.
Qatar has also strongly backed Egypt's Muslim Brotherhood, outlawed since the Egyptian military overthrew an elected Islamist president in 2013, and has given refuge to many foreign Islamists including from Hamas and the Taliban.
Proclaiming a "caliphate" straddling parts of Iraq and Syria, Islamic State has overrun broad swathes of Sunni Muslim-populated northern and western Iraq with little resistance. They have pushed back Kurdish regional forces allied with the Baghdad central government and driven tens of thousands of minority communities including Christians and Yazidis from their homes.
Islamic State circulated a video on Tuesday that purported to show the beheading of American journalist James Foley in revenge for US air strikes against the insurgents in Iraq.
Germany's foreign and defence ministers said on Wednesday that Germany was prepared to send arms to Kurdish security forces in northern Iraq fighting Islamic State and would immediately deliver military equipment such as helmets and security vests.