Slovenians vote in a referendum on a border deal with Croatia today which could affect their southern neighbour’s potential EU membership.
Ljubljana blocked Croatia’s accession talks for most of last year until the two countries agreed a deal in September.
Under the agreement, an international team would settle the border dispute that dates back to the break-up of Yugoslavia nearly 20 years ago.
Slovenia claims direct access to international waters, which could force Croatia to cede some of the sea it considers its own.
The government says the deal is the best it can get for Slovenia. The right wing opposition says it is bad for the country.
Croatia has already ratified the accord on international arbitration, which would be binding on both countries.
But unless the Slovenian people agree to it in the referendum, Ljubljana is likely to continue using its EU veto to block Zagreb’s application to join.
Slovenia is the only former Yugoslav state to have joined the European Union. Croatia hopes to conclude membership this year and join in 2012.