Peru's government bankruptcy agency, Indecopi, said Tuesday it has officially opened an investigation into Doe Run Peru's financial situation, Dow Jones Daily Bankruptcy Review reported. An Indecopi spokeswoman said creditors have 30 days as of Monday to file credit recovery paperwork. The government has taken a hard line against the company in recent weeks, saying it would start the legal and regulatory process of removing Doe Run's ownership of the plant in the town of La Oroya. Doe Run, a unit of U.S.-based Renco Group Inc., shuttered the polymetallic smelter, which normally produces copper, lead and zinc, more than a year ago, after a cutoff in bank loans prevented it from paying for metal concentrates. Peru's mining ministry says Doe Run Peru has failed, among other things, to complete an environmental upgrade to its sulfuric acid plant. It also failed to meet a government restart deadline of July 27. Environmentalists have described La Oroya, about 200 kilometers east of Peru's capital Lima, as one of the most polluted places on earth. Doe Run has been fighting back however, saying it is still in the process of finalizing agreements with creditors, and, that it had made "significant progress" towards restarting the smelter.