Anvisa said there were faults in all clinical studies of the vaccine’s development, as well as absent or insufficient data.
Brazil has banned the import of the Russian COVID-19 vaccine Sputnik V. As per a statement from Brazil's health regulator, "The five-person board of the Brazilian Health Regulatory Agency unanimously decided that consistent and trustworthy data required was lacking for approval of the requests from 10 states."
Brazil alleges that batches they tested carried a live version of a common cold-causing virus.
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The country's scientists have also backed Brazil's decision to stop the import of Sputnik V. Top virologist Angela Rasmussen has told AFP that the finding "raises questions about the integrity of the manufacturing processes" and may be a safety issue for people with weaker immune systems if the problem were found to be widespread.
According to a slideshow uploaded online, scientists at Anvisa, Brazil's health regulator, said they tested samples of the booster shot and found it was "replication-competent" -- meaning that once inside the body, the adenovirus can continue to multiply.
Sputnik V | All your questions answered
They added that this had likely occurred because of a manufacturing problem called "recombination," in which the modified adenovirus had gained back the genes it needed to replicate while it was being grown inside engineered human cells in a lab.
The Russian Direct Investment Fund said in a three-page statement that “no replication-competent adenoviruses were ever found in any of the Sputnik V vaccine batches produced.”
It was also more pointed in its criticism, saying that dozens of national health regulators have approved Sputnik V and Anvisa's decision was “of a political nature and has nothing to do with the regulator’s access to information or science.”
Read: Dr Reddy's expects first lot of Russia's COVID-19 vaccine Sputnik V by May end
In India, the Drug Controller General of India (DCGI) approved the Sputnik V COVID-19 vaccine for emergency use on April 13.
This is the third vaccine, and the first foreign jab, against the novel coronavirus to get emergency use authorisation in the country after Covishield, developed by Oxford University-AstraZeneca and manufactured by the Serum Institute of India (SII), and Bharat Biotech’s Covaxin.
Indian pharmaceutical company Dr Reddy's Laboratories has collaborated with the RDIF to conduct the bridge clinical trials for Sputnik V in India.Click here for Moneycontrol's full coverage of the COVID-19 outbreak