Brazilian health regulators have issued a scathing rebuke of Russia’s Sputnik V coronavirus vaccine, rejecting the shot’s approval in a decision late Monday that could affect its use elsewhere in the world.

The ruling from Brazil’s Health Regulatory Agency, or Anvisa, cited a range of concerns with the vaccine’s development and production, including what it said was a lack of quality control and efficacy data, as well as little if any information on the shot’s adverse effects.

It was not the first time that health authorities have raised concerns about Sputnik V, which was hailed as “safe” and more than 91 percent effective in a peer-reviewed article in the Lancet in February.

Earlier this month, Slovakia’s pharmaceutical regulator scrapped a batch of Sputnik V doses it said did not share “the same characteristics and properties” as those examined by the Lancet. German Chancellor Angela Merkel also said this week that the European Union’s medicines agency had not yet received enough information to approve the vaccine for use inside the bloc.

The fresh critique Monday from South America’s most populous nation further threatened to undermine Moscow’s attempts to use Sputnik V as a tool of soft power there and around the globe.

The evaluation by Brazilian regulators followed a request from 14 of Brazil’s states to import the doses as the country battled a devastating wave of coronavirus infections. Despite the surge, however, the researchers said they could not confidently endorse the vaccine.

“Flaws … were identified in all stages of clinical studies,” Anvisa said in its statement, adding that there weren’t “any manufacturing conditions identified that demonstrate that the products are consistently produced and controlled.”

The agency said it had dispatched an inspection mission to Russia but was barred from accessing the facilities of the Gamaleya Institute, which developed the vaccine.

The makers of Sputnik V fired back on the vaccine’s official Twitter account, calling the decision “political” and saying it had “nothing to do with access to information or science.”

The account pointed to a January report from the U.S. Department of Health and Human Services that appeared to admit that U.S. officials had worked to persuade Brazil to rebuff the vaccine.

Kremlin spokesman Dmitry Peskov said Tuesday that Russia was willing to provide Brazil with extra data if necessary.

“The contacts will continue. If any information is lacking, it will be provided,” Peskov said, adding that there is massive global demand for the vaccine.

The Gamaleya Institute and Russian Direct Investment Fund (RDIF), which backs and markets the shot, say that Sputnik V has been registered in more than 60 countries. It has already been distributed in several places, including Argentina, Belarus, Iran and Syria.

The World Health Organization said Tuesday that no date was scheduled to evaluate Sputnik V’s clinical data for emergency use listing.

“On Sputnik, we are still waiting, we are still in the back-and-forth stage. So we don’t have a review meeting scheduled yet,” WHO spokeswoman Margaret Harris told a briefing in Geneva, Reuters reported.

Last week, the RDIF claimed that its efficacy rate had reached 97.6 percent based on an analysis of 3.8 million Russians who were given the vaccine, which requires two doses.

The organization said that the analysis compared infection rates among vaccinated and unvaccinated Russians and that the data would be published in a peer-reviewed medical journal next month.

“I hope that, in the shortest possible time, Sputnik V’s lack of information will be resolved,” said Anvisa board of directors member Cristiane Rose Jourdan Gomes.

Cunningham reported from Istanbul, Dixon from Moscow.