Turkish President Recep Tayyip Erdogan's son Bilal on Wednesday said he had temporarily moved to Italy to complete his doctoral studies but denied fleeing Turkey after being implicated in a corruption scandal.

Bilal was one of the main protagonists implicated in corruption allegations that exploded in December 2013 against the president's inner circle and were bitterly denied by Erdogan, then premier.

The Russian air campaign in Syria has thrown an immense obstacle in the way of President Recep Tayyip Erdogan's vision for the future of the country, enraging the Turkish leader and leaving Ankara increasingly sidelined.

Russia's air strikes are aimed at propping up the regime of President Bashar Assad, the very ruler who Turkey has for years insisted must be ousted if there is to be any solution to the Syrian crisis.

Turkish Prime Minister Ahmet Davutoglu Wednesday said only two Russian air strikes in Syria had targeted Islamic State jihadists and warned that Ankara would not make any concessions about the security of its borders.

His comments came after Russian warplanes twice violated the airspace of key NATO member Turkey in the last days.

NATO Secretary General Jens Stoltenberg said Tuesday that Russian violations of Turkish airspace were "not an accident" after Turkey complained of two incursions by Moscow's jets.

"For us, this does not look like an accident, it is a serious violation," Stoltenberg told reporters at NATO headquarters in Brussels ahead of a meeting of the alliance's defense ministers later this week.

Turkish President Recep Tayyip Erdogan and EU head Donald Tusk said Monday they had discussed Ankara's controversial plan for a safe zone cleared of Islamic State jihadist fighters in northern Syria.

"The European Union is ready to take up all issues with Turkey so we also discussed a possible buffer zone in Syria," Tusk said after meeting Erdogan for talks in Brussels dominated by the migrant crisis and the Syrian conflict.

Turkey warned Russia on Monday against violations of its airspace by warplanes straying over the border from Syria, as NATO called an emergency meeting over the "unacceptable" intrusion.

Ankara, a NATO member, protested to Moscow after its F-16 jets intercepted a Russian fighter plane that violated its air space near the Syrian border over the weekend, forcing it to turn back.

A Turkish woman was killed and her male partner badly wounded in an apparent double suicide bid on Istanbul's best known shopping street, reports said Saturday.

The woman, Zeren Buke Toku, and her partner, Nazif Tugrul Saglam, sat on a pavement on the bustling Istiklal Avenue, where several other young people were out late Saturday, some drinking and others making music, Dogan news agency reported.

Turkish President Recep Tayyip Erdogan on Saturday urged Russian counterpart Vladimir Putin to reconsider Moscow's bombing campaign in Syria, accusing the Russian military of turning a blind eye to the killing of dozens of civilians.

Speaking in an interview with Al-Jazeera Arabic, Erdogan expressed anger that whereas Moscow had informed Ankara it would be attacking Islamic State (IS) jihadists in Syria, it had in fact targeted moderate Syrian rebels.

Turkish Prime Minister Ahmet Davutoglu on Friday accused Russia of targeting moderate Syrian rebels in its air strikes in Syria to prop up the regime of President Bashar Assad.

Speaking to Turkish reporters on his plane as he returned from the U.N. General Assembly in New York, Davutoglu rejected Moscow's insistence that its campaign of air strikes launched this week was aimed at Islamic State (IS) jihadists.

Syria cannot be forced to choose between President Bashar Assad and "terrorist groups" like the Islamic State (IS) organization, Turkish President Recep Tayyip Erdogan said Thursday.

Erdogan -- who has always rejected cooperation with Assad as a solution in the fight against IS -- was addressing the Turkish parliament as Russia launched air strikes in Syria in support of the regime.