Who administers direct democracy mechanisms at the national level?

Note in the EMB website: 

"Although not explicitly specified by the Law on Referendum and People’s Initiative, The Republic Electoral Commission may also be given the responsibility to conduct the Republic Referendum.   Namely, by virtue of the Article 13 of the said law, it is laid out that the responsible bodies for conducting referendum are the commission and the electoral boards, provided that the referendum commission shall be formed by the body announcing the referendum, and the commission shall then form the electoral boards. Thereby, by the Decision calling a Republic Referendum to endorse the new Constitution of the Republic of Serbia of September 30, 2006, the National Assembly prescribed that the Republic Electoral Commission would be in charge of the administration of that Referendum."