According to the FIS, the International Olympic Committee's ban on Sochi 2014 50km gold medallist Alexander Legkov and five of his compatriots was not legally-binding proof of their guilt.
"In consequence the FIS is obliged to wait on the conclusions from the IOC's disciplinary commission and the evidence before taking other measures," the FIS explained in a statement.
THE IOC's executive committee meets in Lausanne from December 5-7 to rule on whether to allow Russia, accused of state-sponsored doping, to compete at the 2018 Olympic Games in Pyeongchang.
The FIS's stance on the six is likely to trigger uproar from rival competitors with the first leg of the World Cup season staged at Ruka in Finland from Friday.
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Canada's 2011 world relay champion Devon Kershaw fumed before the FIS announced their decision: "The fact that... those suspended for life by the IOC can still win races shows that our sport has become a Mickey Mouse club."
His compatriot Alex Harvey blasted the situation as "shameful".
German skier Andreas Katz said: "It's not possible cross country skiers banned from the Olympic Games can take part in the World Cup."
In December 2016, the FIS suspended Legkov and the five other skiers cited in the World Anti-Doping Agency commissioned McLaren report, which alleged state-sponsored doping in Russia from 2011 to 2015.
The investigation said the cheating peaked at the 2014 Winter Olympics in the Black Sea resort of Sochi where Russian secret agents engineered an elaborate system of state-backed doping.
Last week WADA announced it was maintaining its suspension of Russia in a move described by the Kremlin as "unfair".