A former Russian diplomatic official and an Argentinian police officer are among those arrested in connection with a large cocaine seizure at the Russian embassy in Buenos Aires that prompted a year-long investigation into an international drug ring, officials have said.

The Argentinian security minister, Patricia Bullrich, said the 389 kilos (860 pounds) of cocaine were hidden inside luggage seized in December 2016. The Russian-Argentines Alexander Chikalo, who is suspected of being in charge of the logistics, and Ivan Blizniouk, a police officer accused of providing contacts to jump through customs controls, were arrested on Wednesday.

The investigation began after Victor Koronelli, the Russian ambassador to Argentina, and three members of the Russian federal security service told Bullrich of their suspicions about the diplomatic luggage found at a school annexed to the embassy.

After authorities confirmed that there were drugs inside the 16 pieces of luggage, they devised a plan to catch the criminals, swapping the cocaine for flour and placing a GPS to track the luggage.

“This has been one of the most complex and extravagant drug-dealing operations that Argentina has faced,” Bullrich said.

“At 3 am we had to send people from the border police to buy the 389 kilograms of flour to the central market [in Buenos Aires] because no one had 389 kilograms in a warehouse,” she said. “The drugs never travelled to Russia. Only the flour travelled.”

The luggage was flown to Russia in 2017. Bullrich said three Argentine customs officials journeyed to Russia to monitor the delivery, and that two men, Ishtimir Khudzhmov and Vladimir Kalmykov, were arrested when they went to collect the cargo.

A suspect, whom Bullrich referred to only as K, was in charge of buying the drug and introducing it to the embassy in Argentina. He is still at large in Germany and is wanted under an international arrest warrant.

The logistics were also coordinated by a former embassy official, Ali Abyanov, who was arrested in his Moscow apartment.

Authorities said the drugs had a street value in Russia of about $61m (£44m).