Vienna (AFP) – European Union Commission chief Jean-Claude Juncker on Friday warned of a new war in the Balkans if Bosnia, Albania, Serbia, Macedonia, Montenegro and Kosovo do not feel the EU is serious about offering them future membership.

“If, in Europe’s highly complicated landscape, the impression arises that we’re not serious about offering the prospect of EU membership to the western Balkans, then we might see later — and probably even sooner — what we saw in Balkans in the 1990s,” Juncker said in a speech to the Austrian parliament.

The six Balkan states — which during the 1990s formed the battleground to Europe’s deadliest conflict since World War II that led to the break-up of former Yugoslavia — are currently at different stages of accession talks with the EU.

While membership negotiations have officially started with Serbia and Montenegro, Albania and Macedonia are still in the waiting room to talks and classified as “candidate countries”. Bosnia and Kosovo are listed as “potential candidates”.

Juncker already said last December that expanding into the Balkans was vital to maintain stability in the region and he expected Serbia and Montenegro to join the bloc by 2025.

Nevertheless, the road to full EU membership for those states was “still very long”, Juncker said.

While some of the countries had made progress, “that progress still hasn’t gone far enough.”

He suggested that the EU could offer the states a sort of “economic area where they can partially behave as they will eventually do as full member states.”

And Juncker reiterated that he didn’t see any of them attaining full membership “before 2025, and even then it won’t be quick”.

The EU must “tend to the west Balkans intensively and help where necessary,” the EU Commission chief said.

It should “ensure it is understood that all border conflicts between the west Balkan states must be resolved before the membership can be attained,” he said.

Among the most pressing issues is the status of Kosovo, which unilaterally declared independence from Serbia in 2008, but which Belgrade still refuses to recognise.

Juncker was in Vienna to attend the centenary celebrations marking the foundation of the Republic of Austria.