Tensions are rising in the eastern Mediterranean as neighbours and Nato allies Turkey and Greece engage in a stand-off over potentially significant oil and gas reserves in waters that Athens says are indisputably Greek. Last week Turkey sent a seismic survey vessel accompanied by naval ships to an area just off the Greek island of Kastellorizo and says it plans to continue its search until 23 August.

Greece says this is a clear violation of its continental shelf and territorial waters, while Turkey has argued that islands cannot have continental shelves. A similar dispute was resolved in July after an intervention by German Chancellor Angela Merkel, which lead to Turkish President Recep Tayyip Erdogan saying that Ankara was prepared for negotiations without conditions.

Turkey’s latest move is in the wake of a deal signed at the beginning of August between Greece and Egypt to create an exclusive economic zone in an area in the eastern Mediterranean that contains oil and gas reserves. This deal conflicts with one made between Turkey and the UN-backed Libyan government at the end of last year – a deal which Greece says it does not recognise.