Steel maker Arcelor has started legal action in the United States against Mittal, the company which is trying to buy it.
The law suit claims Mittal is using technology for which Arcelor holds the patents.
Arcelor said this is just about defending intellectual property rights and has nothing to do with Mittal’s takeover bid.
It comes immediately after Arcelor rejected the idea of negotiations with billionaire steel boss Lakshmi Mittal. The Luxembourg-based company said he had not provided enough information about his company.
A Mittal spokesman said: “We believe that the lawsuit is without merit” and added that they had not infringed Arcelor’s patent.
This latest argument between the top two steel companies centers on a technology that strengthens the metal sheets used to make car bodies.
Arcelor and Mittal are both trying to become leaders in the world’s car-steel market.
Mittal is the number one supplier in the United States with clients such as General Motors, while Arcelor supplies the steel for half the cars made in Europe.