Turkey and Greece need to focus on a positive agenda in their bilateral relations, Prime Minister Binali Yıldırım told his Greek counterpart Alexis Tsipras in a phone call on Thursday.

According to the prime ministry sources, Yıldırım said the communication channels need to remain open and both sides should treat their problems in a constructive way in the conversation.

"The two prime ministers agreed to keep open channels of communication in the coming period, and to strengthen dialogue between the two countries in future," a statement from Tsipras' office said.

Yıldırım also offered condolences over the death of the pilot who was killed in a fighter jet crash earlier Thursday.

The Greek air force said pilot Georgios Baltadoros, 34, was fatally injured when his Mirage 2000-5 fell into the Aegean Sea while preparing to land "after concluding an operational mission."

The Greek armed forces will observe a three-day period of mourning over the accident, the defense ministry said.

Reports said the pilot, a father of two, may have blacked out during a combat exercise on the return home.

Patrolling has intensified in recent weeks amid a spike in tensions between Greece and Turkey and near-daily mock dogfights in disputed airspace.

The control of territorial waters and airspace in the Aegean Sea remains a problematic issue between the two countries. Citing bilateral and international treaties, Turkey says both countries have six-nautical-mile-wide territorial waters and airspace around their respective mainland and islands.

In contrast, Greece, citing international law, wants to increase its territorial waters to 12 nautical miles, which would leave practically the whole Aegean Sea under Greek control. Through a parliamentary motion in 1995, Turkey declared unilateral action by arguing that, if Greece were to extend the boundary to 12 nautical miles it would be considered a casus belli. Greece also unilaterally considers its airspace as 10 nautical miles, which is rejected by Turkey.