BERLIN — BioNTech says it has starting manufacturing its COVID-19 vaccine at a new site in Germany, an important step toward increasing global supplies of one of the main vaccines against the coronavirus.

BioNTech, a German company that partnered with Pfizer to produce the first vaccine approved for use in Europe and the U.S., said Wednesday that it has started the manufacturing process at Marburg in central Germany by producing mRNA, the active pharmaceutical ingredient of the product.

The company said that quality tests will be performed internally and externally before the vaccine is released, and the new facility’s production processes will need approval from the European Medicines Agency so that the vaccine can be shipped. The first vaccines manufactured in Marburg are scheduled for distribution in early April.

The site, which BioNTech purchased from Switzerland’s Novartis, will be able to produce up to 750 million doses of the COVID-19 vaccine per year once fully operational.

An initial shortage of production capacity has been a key bottleneck in the rollout of vaccines, particularly in the European Union.