Magistrates have opened a corruption investigation into Italy’s ILVA steel plant on suspicion bribes may have been paid for environmental reports playing down the scale of pollution at the site, a judicial official said on Thursday.

Accusations of pollution there have become a problem for the government of Prime Minister Mario Monti as ILVA is one of the few big industrial plants in the impoverished southern region, employing 12,000 people and supporting thousands of other jobs indirectly.

Several executives of the family-owned Riva group, which owns the plant, as well as a local official in the Taranto area have been placed under investigation into possible corruption, the judicial official said.

A spokesman for Riva declined to comment when contacted by telephone.

Last month, magistrates ordered the plant to be partially closed down because of fears that dioxins and other chemicals pumped from the site may have led to hundreds of deaths in the past 13 years around Taranto in the "heel" of Italy.

A separate investigation into the environmental damage is already underway and eight executives have been placed under house arrest over the case.

Industry Minister Corrado Passera and Environment Minister Corrado Clini are due to visit the plant on Friday.

The government, facing a deepening economic recession that has dragged Italy ever further into the euro zone financial crisis, has criticised last month’s ruling by magistrates and said it is ready to appeal against the decision to order a partial closure.

"The biggest job we have at the moment is making sure that we avoid the definitive closure of ILVA in Taranto," Passera told the weekly Oggi in an interview.

ILVA, one of Europe’s biggest steel makers, is responsible for almost a third of Italy’s steel output and its closure would be very damaging for the south, an underdeveloped region plagued by high unemployment and organised crime.

But health ministry figures indicate that deaths from cancer in the region are 15 percent above the national average and lung cancer death rates 30 percent higher.

The government expects to pass a decree by Sept. 30 outlining steps the plant must take to reduce pollution.

According to prosecutors, noxious fumes from the plant have caused around 400 deaths over the past 13 years. The company says the situation has improved significantly recently.