Argentine police said last week they had seized nearly 400 kilos (880 pounds) of cocaine worth some $62 million (50 million euros) hidden in suitcases in the Russian embassy school.
Russia's foreign ministry has said that the sting operation culminating in December was in fact the result of a joint effort by the countries' law enforcement agencies.
Deputy foreign minister Sergei Ryabkov on Wednesday lashed out at what he called "targeted efforts to smear" the operation, RIA Novosti state news agency reported.
Three Russians were detained in Moscow in December, the ministry said, including the embassy's former maintenance manager. Argentina has also detained two suspects.
Ryabkov attacked journalists and bloggers for what he described as "dreaming up all kinds of non-existent versions."
In Russian media there have been allegations that an official plane was flying the cocaine to Russia during the sting, which the foreign ministry has denied.
According to Argentina's Security Minister Patricia Bullrich, the drugs were substituted with flour and devices were placed in the bags to monitor its delivery as part of the operation.
'Customary evasiveness'
Local and international media reports have suggested Russian national security council chief Nikolai Patrushev's plane may have been used in the sting, after Argentine police published on Twitter a photo and video showing the aircraft number.
The presidential administration, part of the Kremlin, denied any involvement of its planes to RIA Novosti.
In a statement, the foreign ministry said a visit to Argentina by Patrushev was unconnected to the case.
The foreign ministry has also said the drug lords had never planned to send the cocaine by diplomatic pouch -- despite a statement to the contrary by Bullrich.
It also denied claims that the suspected mastermind Andrei Kovalchuk -- who is on the run in Germany -- had ever held technical roles at diplomatic missions, as Kommersant business daily reported.
Vedomosti business daily on Wednesday criticised the ministry's "belated and not always consistent explanations."
Such "customary evasiveness in responses and no less customary aggression is hardly productive," it wrote.
The Kremlin on Wednesday refused to comment on the scandal, with President Vladimir Putin's spokesman Dmitry Peskov telling journalists: "This is the prerogative of the foreign ministry."
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