The demonstration, to take place at Thyssenkrupp's steel hub in Duisburg, comes after weeks of uncertainty over whether Berlin will make good on its commitment to co-fund the so-called direct reduction iron (DRI) facility.
"The Federal Government's hesitation is life-threatening," Juergen Kerner, member of the powerful IG Metall labour union and deputy chairman of Thyssenkrupp's supervisory board, was quoted as saying in a union handout seen by Reuters.
"And not only for Thyssenkrupp Steel."
Germany's Economy Ministry, led by Robert Habeck, has pledged support for the project in the past but is now considering cutting the level of aid, the handout, dated June 1, read.
Sources said the government is expected to add at least 1 billion euros ($1.1 billion) in funds for the DRI facility, which would drastically cut emissions in steelmaking, among the most carbon intense industrial production techniques.
The DRI investment will be among topics to be discussed at a supervisory board meeting scheduled for June 23, according to people familiar with the matter. Labour representatives have threatened that the investment decision could be revoked.
Workers have invited Habeck to the protests, also expressing fears among workers over the future of Thyssenkrupp's steel division, which currently being set up for a partial sale or other forms of a standalone future.
Germany's Economy Ministry had no immediate comment. It recently said that it continued to support the project but was awaiting state aid clearance from the European Commission.
($1 = 0.9084 euros)
