Yes, it is possible to complete an internship. Please contact the Career Service for detailed information: http://www.fu-berlin.de/sites/career/internationales/Internationale-Studierende/index.html
(Unfortunately the website information is available in German only. If you need any help please contact the Career Service office.)
Important: We do not grant ECTS for internships! Internships may only be graded and credited by the home university.