Slovenia has used the six-month period of preparations for implementation as stipulated by the border arbitration agreement to draw up legislation implementing the new border line.

Croatia, on the other hand, insists the arbitration procedure was compromised beyond repair by a Slovenian judge's misdeeds and considers the arbitration award null and void.

The focus in the coming days will be on the sea border given that there had been hundreds of incidents around the bordering Bay of Piran in the past two and a half decades.

Since the border was announced in June, Slovenian police were merely warning fishermen and patrol boats crossing the newly determined border line, which runs south of the median line in the Piran Bay after Slovenia was granted 80% of the bay.

From today police patrols plan to start sanctioning violations.

Croatian fishermen have been instructed by Croatian police to continue with business as usual, meaning fishing halfway into Piran Bay, into the area Slovenia now considers to be its territorial waters.

Croatian boats are allowed to fish there, but they need to get permits from Slovenian authorities. If they don't have permits, they will be liable for fines that can run into thousands of euro.