(ANSA) - Friday, July 27 - Thousands of steel workers in the southern port city Taranto mobilized in protest against a court-ordered partial shutdown of their employer, the ILVA steel plant, on Friday. A Taranto judge ordered on Thursday the shutdown of six areas of Italy's largest steel plant - which employs over 11,000 people - as well as the house arrest of eight current and former managers. Prosecutors charge that the steel plant's toxic fumes and dust endanger the lives of thousands of workers and nearby residents, and have caused hundreds of deaths and high rates of illness. The main labor unions at the steel plant - UILM, FIOM and FIM - called an indefinite strike Friday, leaving just the few workers in command posts to care for key facilities. The unions decided to occupy all entrances to the city of Taranto, and called for the intervention of Italian Premier Mario Monti. Steel workers blockaded state road 100, connecting Taranto to Bari, and state road 106, connecting Taranto to the Ionian coast. Police worked to redirect traffic through secondary roads, while local public transportation suffered serious disruptions, with buses stuck or unable to complete their routes. In northern Italy, 200 ILVA workers in Genoa streamed out of the company's Conigliano plant gates to protest the Taranto plant closure. The Genovese plant relies heavily on materials furnished from the Taranto plant for its own production. "In five days we will no longer have material to work with," said Franco Grondona, secretary of Genoa's FIOM-CGIL unions. The Genoa workers marched to the local prefecture, where prefect Francesco Antonio Musolino persuaded the procession to dissolve. Musolino reassured union leaders that a court re-examining the shutdown order could very soon repeal the closure. Grondona vowed to re-examine the issue Monday.