Turkey says Greece must coordinate research activities in contested Aegean waters

Turkey's defence ministry said on Thursday that Ankara has issued a maritime notice pushing Greece to coordinate with Ankara on all research activities in parts of the Aegean Sea that Turkey sees as its continental shelf.

Ties between the NATO allies, but historic rivals, have improved in recent years but they remain at odds over where their continental shelves begin and end in the Aegean - an area believed to hold significant energy potential and with implications for overflights and airspace.

Turkey recently issued a Navtex - a legal advisory message to mariners - outlining objections to Greece's activities in the Aegean Sea that Ankara says violate international law and demanding it coordinate these.

In a first, Ankara issued the notice without an expiration date. The sides' previous advisories were temporary, in response to their respective activities in the region.

The move could potentially fuel tensions between the allies as they seek energy resources in the eastern Mediterranean, and impact operations by vessels of companies operating in the area.

Earlier this month, Greece's foreign minister said its government had plans to extend its territorial waters further, including potentially in the Aegean Sea. In 1995, the Turkish parliament declared a "casus belli", or cause for war, if Greece unilaterally extended its waters beyond six nautical miles in the Aegean, a position Athens says violates international maritime law.

Greece says the only issue it is prepared to discuss with Turkey is the demarcation of their maritime zones, including continental shelves and exclusive economic zones.