Italian group ILVA said it might have to close its Taranto plant after judges ordered the seizure of steel and semi-finished products as part of a corruption probe that saw several managers arrested on Monday.

Prosecutors ordered the arrest of seven people on suspicion of bribing officials to cover up a health and environmental scandal at the sprawling site in southern Italy, police said.

Justice system officials said the prosecutors arrested Emilio Riva, chairman of the group that owns ILVA, and six others including his son Fabio...