Pinera hits out at the move, claiming he was already absolved of any guilt in a 2017 investigation
The Chilean public prosecutor's office on Friday opened an investigation into President Sebastian Pinera over the sale of a mining company through a firm owned by his children, which appeared in the Pandora Papers leaks.
Attorney General Jorge Abbott opened the probe after the Pandora Papers revealed the sale of the Dominga mining company by a firm "linked to the family of President Pinera," said Marta Herrera, head of the anti-corruption unit in the public prosecutor's office.
Pinera hit out at the move, claiming he had already been absolved of any guilt in a 2017 investigation.
"I have full confidence that the courts, as they have already done, will confirm there were no irregularities and also my total innocence," said Pinera.
The sale of the mine to one of Pinera's closest friends dates to 2010, during his previous term as president.
"As president of Chile I have never, never carried out any action nor management related to Dominga Mining," added Pinera, who took no questions from journalists.
Herrera said the public prosecutor's office took the decision to investigate because of the possibility that the deal involved "bribery, eventual tax crimes, matters that will all ultimately be the subject of an investigation."
The case is due to be led by the public prosecutor in the region of Valparaiso, to the north of the capital Santiago.
Herrera said bribery convictions carried a prison sentence of five years.
According to an investigation by two local media, CIPER and LaBot that are part of the International Consortium of Investigative Journalists (ICIJ) that produced the so-called Pandora Papers, Dominga was sold to businessman Carlos Alberto Delano, a friend of Pinera's, for $152 million in a deal carried out in the British Virgin Islands, a well-known tax haven.
The investigation found that the payment was due to be staggered over three instalments with a clause that stated the final instalment was dependent on "not establishing an area of environmental protection in the area of the mining company's operations, as environmentalists are demanding."
According to the investigation, the Pinera government did not create a protected area around the site of the mine in question.
On Monday, Pinera denied that there was any conflict of interest in the mine's sale.
He insisted that he knew nothing of the deal, because during his first presidency from 2010-14 he said he put the administration of his assets in blind trusts.
"The decision of the administration of these assets to sell Dominga Mine in 2010, which I was not informed about, was precisely to avoid any trace of conflict of interests," said conservative Pinera, a 71-year-old billionaire.
He said the information contained in the Pandora Papers was "not new" and has been public knowledge since 2017.
"It was also investigated in depth by the public ministry and resolved by the courts of justice," he added.
However, on Friday Herrera said the sale of the Dominga mine was not actually "expressly included" in the case that was shelved in 2017.
Dominga owns two open-air mines in the Atacama Desert, 500 kilometres north of Santiago, that are yet to be exploited.
A mining project to do so was approved by a regional court but has yet to be ratified in the supreme court due to appeals.
The project included the construction of a cargo port close to an archipelago that is home to a national park reserve where protected species live, including 80 percent of the world's population of Humboldt penguins.
During his first presidency, Pinera announced the cancellation of the construction of a thermoelectric plant close to the Dominga mine, but took no more steps to protect the area.