Russia has threatened economic retaliation against Turkey and says it is still awaiting a reasonable explanation for the shooting down of its warplane, but Turkey has dismissed the threats as "emotional" and "unfitting".  In an escalating war of words, President Tayyip Erdogan responded to Russian accusations that Turkey has been buying oil and gas from Islamic State in Syria by accusing Syrian President Bashar al-Assad and his backers, which include Moscow, of being the real source of the group's financial and military power.  The shooting down of the jet by the Turkish air force on Tuesday was one of the most serious clashes between a NATO member and Russia.  World leaders have urged both sides to avoid escalation. In an apparent attempt to cool the dispute - and appeal to Western countries - Turkish Prime Minister Ahmet Davutoglu said in a letter to Britain's Times newspaper that Ankara would work with its allies and Russia to "calm tensions".  Earlier, Russian Prime Minister Dmitry Medvedev ordered his government to draw up measures that would include freezing some joint investment projects and restricting food imports from Turkey.  Economy Minister Alexei Ulyukayev said Moscow could put limits on flights to and from Turkey, halt preparations for a joint free trade zone, and restrict high-profile projects, including the TurkStream gas pipeline and a $US20 billion ($A27.66 billion) nuclear power plant Russia is building in Turkey.  Russia's defence ministry meanwhile said it had suspended all co-operation with the Turkish military, including a hotline set up to share information on Russian air strikes in Syria, the TASS news agency reported.  "We are strategic partners ... 'Joint projects may be halted, ties could be cut'? Are such approaches fitting for politicians?," Erdogan said in a speech in Ankara.  "First the politicians and our militaries should sit down and talk about where errors were made and then focus on overcoming those errors on both sides. But instead, if we make emotional statements like this, that wouldn't be right."  Kremlin spokesman Dmitry Peskov said Russia was still awaiting a reasonable answer from Ankara on why it downed the fighter jet. Moscow insists it never left Syrian air space, but Ankara says it crossed the border despite repeated warnings.  The Turkish foreign ministry said diplomatic missions and Turkish business interests in Russia had come under attack and said Russia's ambassador in Ankara had been summoned in protest.  Erdogan told CNN that Russia, not Turkey, should be the one to apologise for the incident. And in an interview with France 24, he said he had called Putin after the jet was shot down but that the Russian leader had not yet called him back.  However, Moscow's response has been carefully calibrated. There is little sign it wants a military escalation, or to jeopardise its main objective in the region: to rally international support for its view on how the conflict in Syria should be resolved.  But it clearly wants to punish Turkey economically.  The head of Russia's tourism agency, Rostourism, said co-operation with Turkey would "obviously" be halted. At least two large Russian tour operators had already said they would stop selling packages to Turkey.  Russians are second only to Germans in terms of the numbers visiting Turkey, bringing in an estimated $US4 billion a year in tourism revenues.  Medvedev meanwhile said Russia may impose restrictions on food imports within days, having already increased checks of Turkish agriculture products, its first public move to curb trade.  The row has also put a brake on new wheat deals between Russia, one of the world's largest wheat exporters, and Turkey, the largest buyer of Russian wheat.
The war of words between Ankara and Moscow over the downing of a Russian fighter jet has escalated, with Russia threatening economic revenge.