"A Russian combat aircraft violated Turkish airspace yesterday, despite repeated warnings by the Turkish authorities," claimed Stoltenberg in a statement, adding that, "Previous incidents have shown how dangerous such behavior is."
He called on Russia to act responsibly and to fully respect NATO airspace. Turkey became a member of the Alliance since 1952.
Stoltenberg urged Russia to take all necessary measures to ensure that such violations do not happen again. "I welcome the direct contacts between Ankara and Moscow, and I call for calm and de-escalation," he added, according to Xinhua News Agency.
NATO Allies agreed in last December to increase the presence of AWACS early warning aircraft over Turkey, according to the statement.
Stoltenberg has highlighted the need to avoid incidents through strengthening international mechanisms in relationship with Russia after a Russian jet downing by Turkey last November.
Meanwhile, according to local daily Hurriyet's report on Saturday, Turkish Air Forces are ready to shoot down any aircraft out of order after Ankara claimed that a Russian SU-34 war plane violated Turkey's airspace on Friday.
Turkish Air Forces have reportedly raised the alert level at air bases to "orange warning" and authorized pilots to shot down any aircraft out of order in case of airspace violation, said the report.
In Moscow on Saturday, Russian defense ministry spokesman Igor Konashenkov dismissed Turkey's accusations as "baseless propaganda," saying that there has not been a single violation of Turkish airspace by Russia air force planes in Syria.
Turkish air force shot down the Russian jet on Nov. 24 claiming it has violated Turkish airspace, whereas Moscow insisted the Su-24 stayed over Syria during its flight.