For decades, crude oil piped in from Russia has flowed into a giant refinery in Schwedt, an industrial city on the Oder River in Germany, providing jobs for thousands of workers and a reliable source of gasoline, jet fuel and heating oil for residents of Berlin.

Now, as European Union member states struggle to agree on the terms of an oil embargo to punish Moscow for its invasion of Ukraine, the Schwedt refinery has become the major stumbling block in Germany’s effort to sever its reliance on Russian oil. The prospect has raised alarm among the refinery’s 1,200 employees.

Germany relies on Russia for about one-third of its oil, and Robert Habeck, the economy minister and vice chancellor, has spent weeks preparing for an embargo, jetting from the United Arab Emirates to Washington to Warsaw, Poland, to line up alternative sources of crude.