'Turkey to retaliate against attack on its vessels in Mediterranean'

"We cannot leave the slightest attack on our civil ships unanswered," Erdogan told reporters in Istanbul on Friday, Xinhua news agency reported.

He said such an incident occurred on Thursday "when the Greek navy tried to harass the Turkish seismic research vessel Oruc Reis, and Turkey's TCG Kemalreis frigate gave the necessary response."

Erdogan added that Oruc Reis will continue its activities in the region until Aug. 23.

The tension between Turkey and Greece, which have been at odds over energy explorations in the Mediterranean, has significantly increased after Turkey dispatched a research ship and two auxiliary navy vessels to the region earlier this week.