Istanbul: NATO's secretary general today accused Russia of deliberately violating Turkish air space in its bombing campaign in Syria, as Turkey's Recep Tayyip Erdogan warned Moscow against continuing such "undesirable" behaviour.
Russian fighter jets entered Turkish air space in two separate incidents at the weekend, prompting Ankara to summon the Russian ambassador twice to protest both violations.
Meanwhile, the Turkish military has said its fighter jets were harassed by a MIG-29 plane from an unidentified country close to Syria on Sunday and Monday.
The anger over Russia's air incursions has intensified controversy over its bombing campaign in Syria which Turkey and the West fears is aimed at keeping President Bashar al-Assad in power.
"For us, this does not look like an accident, it is a serious violation," NATO Secretary General Jens Stoltenberg said in Brussels.
Turkey and Russia have long been at loggerheads over the Syrian conflict, with Ankara seeking the overthrow of Assad while Moscow does everything to keep him in power.
In his toughest remarks yet, the Turkish president lashed out at the incursions, saying "some undesirable steps have been taken and it does not befit Turkey to accept this."
"It is, of course, not possible to remain patient about this," he added on a state visit to Belgium.
Russia and Turkey have in recent years sought to step up cooperation, agreeing to build a new gas pipeline beneath the Black Sea and Turkey's first nuclear power plant, while targeting USD 100 billion in bilateral trade from 2023.
But Erdogan warned that Russia risked losing Turkey as a friend if its behaviour continued.