The bill, which was forwarded to the Slovene parliament on Thursday to be discussed under urgent procedure, defines in a politically unacceptable way Slovenia's position for future talks or arbitration as implied by the the bill, the diplomat said speaking on condition of anonymity.
"It is unacceptable to draw a line in somebody else's yard and then negotiate to which position you will withdraw," the source said.
Croatia is embittered and disappointed with the Slovene move particularly as it occurred only two months after a joint session of the two governments on the Brijuni islands at which they agreed that in the search for solutions to the outstanding border issues they would avoid acts which could prejudge their solution and obstruct the development of good neighbourly relations, the source said.
The only remaining solution is arbitration, which is implied by a provision in the bill stating that the border of the zone will be defined by an international agreement, the source said.
Next week Croatia will launch an initiative to introduce a temporary fishing regime in Piran Bay, which would also include a buffer zone along the demarcation line to avoid incidents between Slovene and Croatian fishermen, the diplomat said.
He dismissed as incorrect interpretations according to which Italy and Croatia are trying to divide the Adriatic, and stressed that the 4 August 2005 agreement between Zagreb and Rome was of a technical nature and that it precisely defined, based on satellite pictures, the demarcation line of the Adriatic continental shelf in line with the 1968 agreement between Italy and the former Socialist Federal Republic of Yugoslavia.
The fact that Slovenia cited the succession to the former Yugoslav federation as the source of its right to declare its zones in the Adriatic would mean that each of the former Yugoslav republics is entitled to its share of the sea, which is untenable. In the 1990s Slovenia cited "a natural right" to access to the open sea, but later changed its rhetoric, the diplomat said.
Slovenia has set as its strategic goal access to the open sea, although the configuration of its coast does not allow it.
Slovenia's territorial waters are closed off by Italy and Croatia's territorial waters, which according to the international law of the sea classifies Slovenia as a "geographically disadvantaged country", just as the country itself has defined itself in several legal documents. Such countries cannot declare exclusive economic zones owing to their geographical position.
The exclusive economic zone is a term used in the UN Convention on the Law of the Sea to denote fishing, ecological and other zones stretching from the outer border of a country's territorial waters to the open sea.
The continental shelf is a term used in the international law of the sea to designate the seabed and subsoil of the open sea adjacent to the outer border of the territorial waters at a certain depth, in which area a coastal country claims sovereign rights for the sake of research and exploitation of the natural resources of the said area.
The 1958 Geneva Convention on the Continental Shelf defines the continental shelf as covering the seabed and subsoil to a depth of 200 metres or, beyond that limit, to where the depth of the superjacent waters admits of the exploitation of the natural resources of the said area.
The sea border between Croatia and Italy has been demarcated also in areas well over 200 metres deep.