Swedish media reported that the two planes came within 90 metres of each other in the air some 80 kilometres southeast of the Swedish city of Malmo on March 3.
"A collision was apparently avoided thanks only to good visibility and the alertness of the passenger plane pilots," the European Leadership Network (ELN) think-tank's report said.
The Scandinavian Airlines Boeing 737 was on its way from Copenhagen to Rome.
The Russian reconnaissance plane "did not transmit its position", said the report "Dangerous Brinkmanship: Close Military Encounters Between Russia and the West in 2014".
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The report listed a total of 45 incidents so far this year -- almost all of them linked to air and naval war games in different parts of the world including the Pacific.
The SAS incident was classified as "high risk", along with two others: the alleged abduction of an Estonian security service operative by Russian agents from an Estonian border post on September 5 and the reports of "foreign underwater activity" off the Swedish coast last month.
Among the 11 were also two cases of Russian aircraft conducting close overflights over Canadian and US ships in the Black Sea and Russian aircraft violating Swedish airspace on a mock "bombing raid" mission and Russian planes conducting a mock attack on the heavily populated Danish island of Bornholm.
The Soviet Union's last leader Mikhail Gorbachev on Saturday warned that the world was on the "brink of a new Cold War" at an event to mark 25 years since the Berlin Wall's fall.