President Recep Tayyip Erdogan has warned Russia not to " play with fire " after reports emerged that Turkish businessmen had been detained in Russia. Moscow said it would suspend visa-free travel with Turkey, and its tourism agency head announced on Friday it will ask more than 9,000 Russians currently in Turkey to return home by the end of December. Relations between the former Cold War antagonists are at their lowest in recent memory after Turkey shot down a Russian fighter jet near the Syrian border on Tuesday. The pilot was machine-gunned dead by rebels on the ground in Syria as he parachuted down. Russia has threatened economic retaliation - a response Erdogan has dismissed as emotional and indecorous. "It is playing with fire to go as far as mistreating our citizens who have gone to Russia," Erdogan told supporters during a speech in Bayburt, in northeast Turkey, on Friday. "We really attach a lot of importance to our relations with Russia... We don't want these relations to suffer harm in any way." Erdogan said he wants to speak with Russian President Vladimir Putin at a climate summit in Paris that starts on Monday. Putin has so far refused to talk with Erdogan because Ankara has not yet apologized for the downing of the jet, a Putin aide said. Erdogan has said Turkey deserves the apology because its air space was violated. The nearly five-year-old Syrian civil war has been complicated by Russian air strikes in defense of President Bashar al-Assad. Turkey and regional powers have accused Russia of targeting moderate armed groups fighting Assad. The frayed relations could also impact two major planned projects - a TurkStream gas pipeline and the Akkuyu nuclear power plant - between the two countries. Turkey and Russia have also sparred over ISIL, with each side accusing the other of being soft on "terrorism".