The right-wing Serbian lawmakers, who passionately oppose Serbia’s bid to join the EU, banged on benches and chanted: “Serbia, Russia, we don’t need the union!”
Some lawmakers held banners saying, “Serbia doesn’t trust Brussels” as Mrs Mogherini struggled to finish her 20-minute speech.
Many of the MPs favour closer ties with Russia, a more traditional ally for the Slavic country.
The interruptions came largely from members of the Serbian Radical Party and the right-wing Dveri party.
Some lawmakers held banners saying, “Serbia doesn’t trust Brussels”
Several nationalist MPs in the Belgrade parliament interrupted the EU chief’s address
We don’t need EU, we don’t trust you
Later, she added: “It’s not nice to be rude to a lady. It’s a matter of politics.
“It’s about a difficult political environment here and in the region, and it is also about different ways of interpreting the path that Serbia has taken.”
She told the half-empty room: “You have a great responsibility. Serbia has always been on the crossroads of different worlds.”
According to the foreign policy chief, the European Union will never be complete without Serbian involvement.
Mrs Mogherini, who is on a tour of the Balkans, told the region that the EU remains open to expansion despite the Brexit decision.
The Serbian lawmakers passionately oppose Serbia’s bid to join the EU
Mogherini called for greater EU expansion over the Balkans
With an election later this year, many have clamored for a pivot towards Russia.
Mr Vucic announced this week that he will meet with Rusian President Vladimir Putin “in the coming weeks”.
Russia recently declared the Western Balkans to be part of its “sphere of influence” and has taken advantage of growing nationalist sentiment and ethnic frictions in the region to reassert its influence there.