MOSCOW — The backers of Russia's Sputnik V vaccine signed a deal Tuesday that could pave the way for production in Italy, a potential major step in Moscow's efforts to expand its vaccine reach in the West.

The deal was announced by the Italian-Russian Chamber of Commerce and Russia's sovereign wealth fund, known as the Russian Direct Investment Fund (RDIF), which supported Sputnik V's development.

But the vaccine still has to win regulatory approval from the European Medicines Agency (EMA) and Italian regulatory authorities before production can go ahead.

Dozens of countries have registered the Sputnik V vaccine, but European Union approval would be seen by Moscow as significant validation of its scientific work and the Kremlin’s attempt to use Sputnik to advance its global influence.

In Russia, vaccine efforts have been underway for months but remain relatively slow outside big cities such as Moscow and St. Petersburg.

Few details of the potential Russia-E.U. deal have been made public. But European governments have been under pressure over their slow rollout of vaccines, including glitches over supply. The European Union has registered three vaccines: the ones developed by Pfizer and BioNTech, Moderna, and AstraZeneca and Oxford.

The deal to manufacture Sputnik V in Italy comes after the E.U. medical regulators last week began a rolling review of Sputnik V, following the publication of interim results on the Russian vaccine in the medical journal the Lancet in February that suggested the vaccine was safe and had an efficacy rate of 91.6 percent.

The deal, first reported by Bloomberg News, would see Swiss pharmaceutical firm Adienne Pharma & Biotech SA manufacture the Russian vaccine in the Milan region, according to the firm’s president, Antonio Francesco Di Naro.

Russia has been battling to overcome global skepticism of its Sputnik V vaccine. Russian authorities went ahead with registration and mass distribution last year, well before the completion of Phase 3 trials, in their effort to be the first to bring a vaccine to the global market.

The Kremlin reacted angrily to comments by EMA Chairwoman Christa Wirthumer-Hoche late Sunday that she would advise European countries against emergency authorization of Sputnik V in Europe before its approval by the EMA.

“It’s somewhat comparable to Russian roulette. I would strongly advise against a national emergency authorization,” she said, speaking on Austrian television, adding there was not sufficient data about the vaccine’s safety. She said the vaccine must meet European Union standards on quality control and efficacy.

“We could have Sputnik V on the market in the future, when we’ve examined the necessary data,” she said.

Kremlin spokesman Dmitry Peskov said Tuesday that her comment was both “unfortunate” and “inappropriate.”

Sputnik V’s developers demanded an apology in a comment posted on Twitter and questioned “possible political interference” in the EMA’s rolling review.

Peskov on Tuesday also dismissed State Department claims that several websites associated with Russian intelligence agencies were spreading disinformation about Western vaccines. He said Russia was against politicizing vaccines. “We don’t understand why such statements have been made, and we will continue to patiently explain that such statements are completely absurd,” Peskov said.

According to the RDIF, Sputnik V has been registered in 46 countries. Russia says it will be ready to provide 50 million vaccine doses to Europe, beginning in June.

RDIF head Kirill Dmitriev told Italian television Sunday that Russia has also formed a partnership with a German firm and is in talks with French companies.