The company said it was providing the "information requested". A police spokesman did not immediately respond to a request for comment.

The Italian government filed an urgent court appeal on Friday to try to stop ArcelorMittal walking away from a 2018 deal to buy the heavily polluting Ilva plant, which employs some 8,200 workers in an area of high unemployment.

ArcelorMittal announced its decision to withdraw from the deal after the government scrapped a guarantee of legal immunity for its managers during the clean-up of the Taranto steel plant.

The government said the group had no legal grounds to pull out of the contract and has accused it of using the immunity issue as a pretext to walk away from Ilva due to heavy losses.

Magistrates in Milan are investigating suspected market manipulation and other offences connected with company property, a source close to the matter said.

On Monday, ArcelorMittal said it would stop a planned shutdown of the plant pending the legal ruling.

A court hearing will take place in Milan on November 27 and Italian Prime Minister Giuseppe Conte has scheduled a meeting with the company this Friday.

(Reporting by Angelo Amante, Emilio Parodi and Alfredo Faieta; editing by Gavin Jones and Jan Harvey)