For 400 years, Carletta Heinz’s family has produced bespoke glass bottles for the world’s leading perfumeries in a factory on the edges of Germany’sFranconian forest.

But Russia’s invasion of Ukraine may force the 38-year-old chief executive to close the business before it enters its fifth century.

In the event of prolonged gas shortages, if Moscow decides to cut supplies to European countries that have imposed sanctions on Russia over the war, “we won’t be able to survive as a company”, she said. “We’d have to shut down the [glass-melting furnaces] completely, we’d lose the workforce . . . and it would be very hard to just restart production after a year or two.”

Heinz-Glas is not the only German company raising the alarm. More than half the natural gas consumed in the country each year comes from Russia — the highest share for any major EU economy — and gas-reliant industries are warning that by winter their operations could be at the mercy of Moscow.

Their fears were heightened on Wednesday when the German government, worried Russia would cut off gas supplies after EU states rebuffed Moscow’s demand to be paid in roubles, activated the first of three warning stages in its emergency supply plan.

Under a law put in place during the oil embargo of the 1970s, German industry would be forced to curtail gas consumption in the event of a shortage, with supplies reserved for critical infrastructure and households.

Such a step would cost Europe’s largest economy tens of billions of euros, estimates suggest, and could plunge it into recession. Union leaders have warned hundreds of thousands of jobs would be at risk.

The German economy could even enter its “worst crisis since the end of the second world war”, Martin Brudermüller, chief executive of BASF, the world’s largest chemical company by sales, told the Frankfurter Allgemeine