"Croatia has now proposed arbitration as perhaps the best way. I personally agree. I have said this already in the past," he told Croatian Radio on the fringes of the 12th annual summit of Central European presidents in Zagreb.
Drnovsek said Croatia and Slovenia had been negotiating "for a very long time" and that he himself had negotiated with Croatian prime ministers for more than 10 years.
He said arbitration would defuse political tensions surrounding the border dispute and have a positive effect on bilateral relations in general.
Slovene Foreign Minister Dimitrij Rupel has been saying the issue should be resolved bilaterally, with the European Union's supervision, as part of Croatia's EU membership negotiations.
He has allowed for the possibility of arbitration only "within European frameworks", namely with the EU being "a witness, arbiter and assistant" and if Croatia proves its "credibility".