Candidates from other countries are not eligible to apply for the UPSC civil services examinations. Specifically, only citizens of India and certain categories of individuals, such as NRIs and Persons of Indian Origin (PIOs), have the right to take these exams. This eligibility criterion is based on the premise that UPSC recruits individuals for civil service positions that primarily serve Indian citizens within the country. Therefore, foreign nationals cannot access positions meant for Indian resources unless they meet the specific conditions outlined by UPSC.