Mexican prosecutors continued to determine if the more than 5,700 doses of Sputnik V vaccine seized in Mexico last week are real or fake. 

Authorities were able to get a hold of the Russian vaccine vials at Campeche International Airport in Mexico, aboard a private plane bound for Honduras, according to The Hill. 

Initially, the Russian Direct Investment Fund (RDIF), which is responsible for the exports of the COVID-19 vaccine, noted that the vials seized by the Mexican authorities are not authentic, Reuters reported.

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Prosecutors in Mexico and Sputnik V Vaccine

But the seized Sputnik V vaccines' authenticity became a mystery when the head of Mexico's customs service noted that the vaccines appeared to be real.

And the prosecutors are now claiming that they do not know if they are authentic or not, Associated Press reported.

"Analysis of the photographs of the seized batch, including the design of the containers and labels, suggest that it is fake," said RDIF in a statement. RDIF also noted that the vaccines, which are now in the authorities' hands, have nothing to do with the original vaccine.

The labels in the seized Sputnik V vaccines feature errors in Russian spelling. Mexico's Medical Safety Commission still has not released what was inside the 1,155 vials of the Sputnik V vaccine. The vials were found inside two coolers packed with ice and sodas.

The Honduran company, Grupo Karims, which was supposed to receive the 5,775 doses, noted that the COVID-19 vaccines are not intended to be sold in their country. 

Instead, they will be given to their employees and their families for free. The company claims that it is their way of helping their workers who have been affected by the COVID-19 pandemic.

Sputnik V Vaccines in Mexico

Mexico received its first shipment of Sputnik V vaccines late last month. The first shipment of Sputnik V vaccines in the country was composed of 200,000 doses that were administered to people aging over 60 living in more impoverished neighborhoods.

Apart from the Sputnik V vaccine, Mexico also got AstraZeneca doses from a plant in India. The country also approved two COVID-19 vaccines from China developed by CanSino and Sinovac.

Meanwhile, the crews and passengers inside the private plane where the Sputnik V vaccine's vials were seized were not detained. 

The seven Honduran crew members and the passengers are staying in a hotel in Campeche. They could not be charged by the Mexican government until the authenticity of the vaccine doses are determined.

The Honduran company did not share any information regarding its purchase of the Sputnik V vaccine and its authenticity. 

The head of Mexico's Custom Service, Horacio Duarte, maintained that the said COVID-19 vaccines were not among the doses purchased by Mexico's government that were used to vaccinate their citizens.

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WATCH: International Demand for Russia's Sputnik V Vaccine Soars - From  ABC News