Exercises by Greek navy ships have forced tankers transferring Russian oil further out into international waters.
The exercises were announced by the country’s Hellenic Navy Hydrographic Service on its website.
They took place in an area off the south coast used for ship-to-ship-transfers of Russian exports.
The activity began on 1 May and will run until 9 May, the governmental body said.
The Laconian Gulf became a key spot for oil transfers following sanctions being placed on Russian sales after the Ukraine invasion.
Since the exercises began, tankers have left the gulf and gathered just to the south, Bloomberg cited data from TankerTrackers as showing.
On a trip to the port of Piraeus last week, Greek shipping minister Christos Sylianides said the safety of the country’s shipping is paramount.
Last month, Denmark briefly shut a shipping lane in the Baltic Sea after similar exercises.
In March, a Black Sea monitoring group claimed a total of 94 tankers had brought Russian oil into European Union waters in defiance of the bloc’s import ban.
The Euromaidan website cited the Ukraine-based Black Sea Institute of Strategic Studies and BlackSea News as saying the vessels imported 82.9m barrels from Black Sea ports between 5 December and 29 February.
Of this, 68% was transported to Greece’s Laconian Gulf for transhipment.
But TradeWinds was told these transhipment voyages and operations take place in international waters and do not breach the ban. Nor is this oil sold into the EU, but exported to Asia.
