Why should you surf job search engines while you are looking for an internship? General job search engines often offer internship positions, too. Moreover, researching job offers may help you identify the organizations that would be of interest to you, even for an internship. Don’t hesitate to apply for an internship with a company, even if no internship position is advertised!
If you are interested in a particular country, you may also find helpful information and internship databases on the website of the embassies and the chambers of commerce. E.g. if you are from India and you are interested in an internship in Germany, take a look at the German embassy in India’s and at the German chamber of commerce in India.