It is prohibited to finance a political entity by foreign states; foreign natural persons and legal entities, except international political associations.
"It is prohibited to finance a political entity by foreign states; foreign natural persons and legal entities, except international political associations; anonymous donors, public institutions, public enterprises, companies and entrepreneurs engaged in services of general interest, institutions and companies with state capital share, other organizations discharging administrative authority; trade unions, associations and other non-profit organizations, churches and religious communities; gaming industry; importers, exporters and manufacturers of excise goods, legal entities and entrepreneurs with due, and unsettled, public revenue obligations, unless set forth otherwise by this Law. Donations from international political associations may not be in money. Financing of political entity by a natural person or legal entity engaged in activities of general interest pursuant to contract with organs of the Republic of Serbia, autonomous province and local government and public services founded by them is prohibited throughout the validity of such contract and for a period of two years subsequent to termination of contractual relations. Acquisition of shares or stock in a legal entity by a political entity is prohibited. Financing of a political entity by an endowment or foundation is prohibited."
Source: Article 12, Law on financing political activities, 2014 consolidated text