An Australian man's attempt to re-enact a perilous open-water refugee journey across the Adriatic Sea has been blocked by Croatian police due to its danger.

Shane Braddock, 34, whose mother is Croatian, planned to kayak across 300 km of the Adriatic from Split in Croatia to Pescara in Italy with fellow adventurer American Ray Fusco.

The dangerous route was used by hundreds of political refugees from the former communist state of Yugoslavia to flee to the west, though few survived the crossing.

But port authorities in Split denied the duo permission to embark on the weekend, saying it was too dangerous without an accompanying rescue boat, and sent police to block the entrance and make sure they stayed in port.

Croatian rescue service spokesman Radovan Linic said: "Heavy shipping traffic and bad weather conditions make that route very treacherous for kayakers."

Braddock, from Perth, insists they are experienced and equipped sufficiently to attempt the crossing despite the risks, and will continue to push for permission.

"We'll do our best to convince them," Braddock said.

"We did not want to have a boat following us because that would not be the same level of an adventure".