Growing numbers of shipowners are avoiding calls at Sevastapol and Crimea ports as the legality of doing business there is increasingly open to question.
EU regulation 692/2014 prohibits the importation into the EU of goods originating from the Crimea or Sevastopol, with an exception for contracts for sale concluded before June 25.
Lloyd's List Intelligence data suggests that numbers of calls are down from 1,098 in the first six months of 2013 to 758 in the first six months of 2014.
The latest sanctions from the European Union bans imports originating in Crimea, said P&I insurer Steamship Mutual, reports Lloyd's List.
Ukrainian authorities are entitled to ask other IMO member states to detain vessels calling in their ports after calling in Crimea.
The ban covers Evpatoria, Kerch, Sevastopol, Feodosia and Yalta, but will likely prove impossible to enforce on territory that is under Russian control.
But the Ukraine is still recognised by the UN's International Maritime Organisation (IMO) as the legitimate ruler of the Crimea.
Insurer Steamship Mutual points said contractual obligations cannot be enforced if performance would be illegal under the law in the place of performance under English law.
But matters could depend on what jurisdiction a dispute is being heard and whether it recognises the Russian annexation of the peninsula.
Many charterparties also include clauses detailing what actions parties may take if voyage orders breach sanctions.
Such clauses do not automatically apply to the Ukraine government's restrictions on port calls, as they have been imposed by individual states rather than multilateral authorities.
