The chairman of Codelco, the world's largest copper company, vowed that his company won't be pressured into changing policies by an explosion on Friday at his home in Santiago that left him with minor injuries.

Oscar Landerretche, who was released from the hospital on Saturday, condemned what he called a "very violent, cowardly attack on my family and myself", Radio Cooperativa reported.

He declined to speculate on who might be responsible, but added that "if anyone thinks that because of something like this, the board of Codelco, its senior executives, or myself are going to act any differently than we have been, ... they are profoundly mistaken", according to a recording of his remarks on Radio Cooperativa's website.

A little-known group calling itself Individualists with Wild Tendencies, claimed responsibility for what it called "an indiscriminate eco-extremist attack" undertaken as payback for environmental damage caused by Codelco's mining activity. The bombing has shaken a country where attacks on company executives or politicians are extremely rare, and where the murder rate is the second-lowest in the Americas, after Canada.

"All my support goes to Oscar Landerretche and his wife, Patricia Medrano," said President Michelle Bachelet, who appointed him to the board in 2014. "My most profound rejection to the attack he suffered."

Landerretche's daughter and maid were also treated for damage to their hearing, Deputy Interior Minister Mahmud Aleuy told reporters. The Massachusetts Institute of Technology-trained economist "received" the explosive device at his residence in the Chilean capital, the state-owned mining company said.

Security stepped up

The device was delivered by a woman and had a return address of the Universidad de Chile, said Landerretche's father, according to Radio Bio Bio. Aleuy declined to comment on the details of the explosion.

Police immediately stepped up security at the homes of other government officials and authorities, Bio Bio reported.

"This is serious", Aleuy said. "We will support the prosecutor in his investigation in any way possible."

Codelo said it "drastically condemns these types of events that will be investigated by the law to clarify the circumstances and identify those responsible".

The mining giant has been enmeshed in a series of disputes with indigenous communities over a planned $18 billion expansion of its mining operations through 2020.

Before being named to the board of state-owned Codelco, Landerretche, 44, taught economics at the University of Chile in Santiago. He is a syndicated newspaper columnist and was chief policy adviser to former president Eduardo Frei Ruiz-Tagle in his unsuccessful 2009 re-election campaign.