Russian President Vladimir Putin says the downing of a Russian plane by Turkey is a 'stab in the back'.
NATO has called an extraordinary meeting (Tuesday 16GMT) to discuss the incident along the Turkey-Syria border.
Moscow says the Su-24 crashed on the Syrian side of the border, and denies it had violated Turkish airspace.
Both pilots ejected from the plane, but Syrian rebel forces say at least one of them is dead.
Russia began air strikes in Syria in late September and has been accused by western powers of supporting the government of Bashar al Assad rather than prioritising the targeting of Islamic State militants.
Moscow correspondent Julia Lyubova says Vladimir Putin has set out a strong response.
IN: "He said…
OUT: …relations."
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ALT:
Moscow correspondent Julia Lyubova says the incident will cause serious damage to Turkey-Russia relations.
IN: "Turkey…
OUT: …further."
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