President Vucic was invited to the EPP Congress as the leader of the Serbian Progressive Party (SNS).
According to Blic, Vucic sent a letter to EPP President, Joseph Daul, containing rationale for his decision.
Here's integral version of the letter:
"Dear President Daul, my dear friend,
Dana Budisavljevic's film "The Diary of Diana Budisavljevic" had its Serbian premiere at Belgrade's Kombank Hall within the program of the 15th Free Zone Festival.
"The European perspective of the Western Balkans, which has been the basis of US engagement in the region for more than 20 years, has not changed and will not change", Matthew Palmer, US Deputy Assistant Secretary of State and US Special Representative for the Western Balkans said.
They walked in a procession in the centre of Zagreb, ending in front of the government building, where protest organisers and union representatives made speeches.
"You have no right to give up the fight for our dignity and for the status of our profession," Sanja Sprem, head of the Union of Croatian Teachers, told protesters.
Montenegro on Wednesday extradited Sasa Sindjelic, a former protected witness in the Montenegro "Coup Plot" trial, to Croatia, where he is to serve a jail sentence over an unrelated case.
It previously arrested Sindjelic, a Serbian national, on the basis of an Interpol "red notice" submitted by Croatia.
Romanian-Dutch duo Horia Tecau/ Jean-Julien Rojer won the men's doubles final of the 2,082,655-EUR Swiss Indoors ATP tournament in Basel, Switzerland, after defeating US double Taylor Fritz /N.4 Tecau-Rojer prevailed in 69 minutes, thus sealing their qualification for the ATP Finals. Tecau-Rojer previously reached the Basel semi-finals in 2015 and 2016.