Pro-Russia Serbian MPs barrack Mogherini

Far-right Serbian MPs from the Serbian Radical Party (SRS) favoring closer links with Russia banged on benches and chanted "Serbia, Russia, we don't need the Union!" during Mogherini's 25-minute address.

Serbia is formally seeking EU membership, but is split between those seeking pro-Western integration and those wanting a close alliance with traditional Slavic partner Russia. Belgrade opened accession talks three years ago after years of delay due to the fallout from the Yugoslav wars of the 1990s.

Banners reading "Serbia doesn't trust Brussels" dotted the room.

Vojislav Seselj, the leader of the SRS, said the chants sent "a clear message that Serbia doesn't want to enter the EU, but wants integration with Russia." The SRS has just 22 out of the 250 legislators.

Mogherini's trip to all six Western Balkans states is designed to lay the groundwork for an EU foreign ministers meeting on Monday and a summit on Thursday, at which EU leaders are expected to reaffirm their commitment "to support stability and to deepen political and economic ties with and within the region," according to an early draft of their joint statement.

The EU has made Serbia's accession conditional on normalizing ties with Kosovo. Serbia's ally Moscow refuses to recognize the 2008 independence of Kosovo, which has an association agreement with the EU.

Uncertainty also surrounds US President Donald Trump's policies on the Balkans, and Russia has been asserting its influence in the region, where tensions have been mounting in relations between Serbia and its former war foes Bosnia and EU member Croatia.

A matter of politics

Barely acknowledging the noise, Mogherini advised the chanting lawmakers "to save their throats for their voters," the daily Blic reported in its online edition.

"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," Mogherini later said of the incident, calling the barracking a "matter of politics."

During her speech, Mogherini said Serbia, the Western Balkans and the EU "are closely joined and need each other," adding that their interconnection is particularly important at what she described as a "delicate" moment of insecurity and tensions in the region and Europe as a whole.

"You have a great responsibility," Mogherini said. "Serbia has always been on the crossroads of different worlds."

"Peace in the Balkans is peace in Europe," Mogherini said at a joint press conference with Aleksandar Vucic, Serbia's prime minister. "We have faced in the recent times - and we might face in the times to come - some attempts to put this into question."

Vucic criticized the ultranationalists' chant during Mogherini's speech as "ungentlemen-like," insisting that Serbia "remains firmly on the European path."

Serbia, which has so far closed six of 35 chapters in its EU membership talks, on Monday opened two more - a move hailed by Vucic as "significant and a message to investors around the world." Serbia hopes to complete all chapters by 2019.

jbh/msh (AP, dpa)