Tensions between Croatia and Serbia rose after Serbian President Aleksandar Vučić was not allowed to visit the World War II memorial.
Vučić planned a private trip to the site of the former Nazi concentration camp at Jasenovac, near the Croatian border with Bosnia and Herzegovina.
But the Zagreb authorities said it was “unacceptable” that they found out about his visit through “unofficial channels” and were not formally notified.
“We would like to emphasize that when planning any visit by foreign officials, the time, nature and program of the visit must be the subject of official communication and the consent of both parties,” Croatian Foreign Minister Gordan Grlich-Radman told reporters.
“It was not a trip to the sea, the president of the country is a protected person,” he added.
Croatia’s decision to block Vučić’s visit sparked outrage in Serbia, with officials calling the block “scandalous”.
Tens of thousands of Croatian Serbs, Jews and Gypsies were massacred by the pro-Nazi authorities at the Jasenovac concentration camp, sometimes referred to as the “Croatian Auschwitz”.
Interior Minister Aleksandar Vulin said that now all Croatian officials will have to officially announce any visit or passage through Serbian territory.
Vulin also threatened that Croatian diplomats would be placed under a “special control regime”.
“It was an anti-European and anti-civilization decision and a gross violation of freedom of movement,” Serbian Prime Minister Ana Branabic told national media.
“I don’t know what our relationship will look like in the future… It sends a chilling signal.”
Relations between Serbia and Croatia remained tense after the collapse of the former Yugoslavia and the war that broke out when Croatia’s Serb minority rebelled against the country’s independence.
over 20,000 people were died in the conflict between 1991 and 1995.
The populist authorities in Serbia insist that the Croatian government has not done enough to acknowledge its past during World War II. Meanwhile, Zagreb accused Belgrade of refusing to acknowledge its role in the 1990s war.
“We see this as a provocation,” Grlich-Radman said on Sunday. “Such a visit is insincere, it is not about honoring the victims.”
Vučić, a former nationalist who supported the Serb uprising in Croatia in the 1990s, also condemned the incident.
“You [Croatia] just do your job,” he wrote. Instagram post on Sunday. “The Serbian people will live and never forget,” he said.