“At BHP Billiton, we have been overcome with sadness and our concern for your community,” Mackenzie told a press conference in Brazil.

“We are deeply sorry, so sorry, to everyone who has, and will suffer, from this terrible tragedy, to the friends and the families of those killed and missing and to those who have lost their homes and their possessions and who feel that their livelihoods may be under threat.

“The devastation that I and we have witnessed on site this morning and around the community is quite heartbreaking, so our thoughts and our prayers are with all of you in this distressing and uncertain time.”

The death toll is current six, with 21 still missing and more than 600 homeless.

Mackenzie said BHP, along with its partner Vale, were working closely with Samarco to support the response effort, including safety, rescue and humanitarian efforts.

He added that the purpose of his visit to Minas Gerais was to better understand how BHP could be the most helpful.

Mackenzie and Vale CEO Murilo Ferreira were joined by BHP iron ore president Jimmy Wilson, Vale executive director, ferrous minerals Peter Poppinga and Samarco CEO Ricardo Vescovi De Aragao on a tour of the affected area.

“I heard great stories of huge courage, heroism and commitment in the response effort and the courage and resilience of the workforce of Samarco, the communities and the responders in the face of this awful event truly inspires me,” Mackenzie said.

“Let me be very clear: we are 100% committed to do everything we can do to support Samarco and make this right.”

BHP and Vale have established an emergency fund to assist the community with rebuilding.

“Samarco will continue to update you on this, the situation and all the support efforts, but please make no mistake: the people of Brazil, the people of Mariana, have my absolute determination that we will fully play our part in helping to rebuild your homes, your community and your spirit,” Mackenzie said.

Responsibility

Brazilian President Dilma Rousseff has spoken to Mackenzie and Ferreira by phone, and has demanded Samarco take full responsibility for the accident.

She yesterday issued Samarco with a 250 million real ($A94 million) preliminary fine for “violating several laws”.

Rousseff, who toured the region yesterday, warned that the company may face further penalties.