Russia's diplomatic mail was not used for cocaine traffic in Argentina, a foreign ministry spokeswoman said on Saturday, after police busted an international ring of drug smugglers.

The investigation started in 2016, when the Russian ambassador to Argentina called local authorities to report that traffickers were trying to move 16 bags of cocaine from the Buenos Aires embassy by way of a diplomatic flight.

Maria Zakharova, the spokeswoman for the Russian foreign ministry, said on social media that the information about smugglers using diplomatic mail "was not true".

The investigation led to the arrest on Wednesday of an Argentine policeman and another citizen of the South American country.

Others involved in the scheme had been arrested in Russia, while one of the leaders of the plot was still on the run, Argentina's Security Minister Patricia Bullrich told reporters earlier this week.

Zakharova said the cocaine was destined for Europe and belonged to a Russian embassy's non-essential employer. She didn't say if he was arrested.