Germany's interior minister has said stolen files detailing hundreds of recruits to the Islamic State militant group can be assumed to be genuine.

Thomas de Maiziere said the information could help with prosecutions of IS fighters, and help prevent future recruitment to the militant group.

Files obtained by German, UK and Syrian opposition media are said to identify IS recruits from at least 40 countries.

Some 22,000 names appear to be listed but most may be duplicates.

Names, addresses, phone numbers and skill sets are listed on official-looking forms.

Documented in Arabic, files were published online by Zaman Al-Wasl, a Qatari-based Syrian news website.