Croatia said Wednesday it would seek international arbitration to resolve a dispute with neighboring Slovenia over control of the part of the Adriatic both countries claim.
Prime Minister Ivo Sanader said Croatia officially asked Slovenia to accept international arbitration. "If we cannot agree, and it's obvious that we cannot, it's best to call the third side" to solve it.
Slovenia said it needed time to review Croatia's request.
Croatia and Slovenia have been arguing over a few sea and land border points unresolved since the two countries gained independence from the former Yugoslavia in 1992.
They agree on 99 percent of their border, but disagree about a few villages and the exact border at sea. Slovenia claims a wider area in the Adriatic, insisting it has an access there to international waters - a claim Croatia fiercely rejects.
On Tuesday, the Slovene parliament declared its epicontinental zone in the Adriatric, which it said entitles it to protect and use the sea bed in that area.
Janez Podobnik, Slovenia's minister for environment, said Slovenia was a "sovereign coastal state with the same rights as Croatia and Italy." The three countries line the northern Adriatic.
Croatia insisted that since Slovenia has no access to the international waters, it also has no right to the epicontinental zone.
The new row comes only a day after the European Union - which insists that its members have good neighborly relations - opened membership talks with Croatia. Slovenia joined the EU last year.
In Brussels, EU foreign affairs chief Javier Solana said Wednesday that "the problems will have to be resolved" between the two before Croatia joins the bloc, the AP reports.
The United States has imposed new sanctions against the Nord Stream 2 gas pipeline project, which still remains under construction