Croatia Airlines has denied reports it intends to launch flights between Zagreb and Belgrade this summer. Last weekend news of the resumption of flights between the two cities swept the media after the airline’s representative in Serbia was quoted by the press as saying flights will be introduced in late May. The announcement was allegedly made at the Belgrade Tourism Fair and carried by Croatian media outlets. However, the Croatian carrier has now denied the reports, saying it will launch flights between Split and Belgrade on May 31 as planned. Flights will operate twice per week and will go head to head with Jat Airways.
The last commercial service ever to operate between Belgrade and Zagreb was on August 6, 1991 by JAT Yugoslav Airlines. However, flights between the two cities were regularly disrupted in the months prior to the suspension due to the refusal of ground staff to handle JAT aircraft in Zagreb. In December 2011, then Croatia Airlines CEO, Srećko Šimunović announced that flights would be launched between the Croatian and Serbian capital during the summer of 2012. However, they never did. On the other hand, Jat Airways has no plans to resume flights to the Croatian capital. It maintains that the two cities are too close and are connected by efficient road infrastructure, rendering services unnecessary. 
This summer, besides Croatia Airlines’ two weekly flights between Split and Belgrade, Jat Airways will also operate between the two cities, four times per week. Furthermore, it will resume seasonal flights to Pula with four weekly flights and another five weekly flights will be operated between Belgrade and Dubrovnik. Services commence in the first week of June. Source; EX-YU aviation news