The Governor General condemned the killing of an activist opposed to a Canadian mine during the last day of a state visit to Mexico while protesters chanted "Canada, get out."

About 50 supporters of Mariano Abarca Roblero were kept about 200 metres from a Mayan women's collective when Michaëlle Jean visited the colonial town of San Cristobal de Las Casas, about five hours from the mine's location.

"We find it deplorable, inexcusable," Jean said in a statement Wednesday. "We will be following this situation closely with the firm hope and conviction that justice will be served."

Abarca Roblero was gunned down in front of his home in southern Chiapas last month. The community leader had been campaigning against a barite mine operated by a subsidiary of Calgary-based Blackfire Exploration. Three men arrested in Abarca Roblero's death have ties to Blackfire.

State authorities, citing environmental concerns, temporarily shut down the mine this week.

In Canada, Blackfire president Brent Willis said the Mexico mine was run in an environmentally responsible way and the company was in no way connected to the killing. Willis said the mine was shut down by state authorities because the company was not properly removing dust from the roads and did not obtain proper permits for both a road and CO2 emissions from new mining equipment.

The company is working on getting those problems fixed and expects the mine to reopen by Monday, Willis said. He denied activists' statements that the mine was harming the environment, saying Mexico has very strict laws that his company has followed to the letter. Rather than open pit mines and heavy chemicals used by some companies, Blackfire mines the barite with excavators along the surface of the ground, Willis said.

"We're running our company ethically and to Canadian standards, and we're following all the environmental guidelines," he said. "We're not involved in any type of pollution."

Of the three men arrested in Abarca Roblero's death, Willis confirmed one is a former employee, one worked as a contractor doing dust control on the roads and one is currently employed as a supervisor at the mine. He denied that any of the men had ever acted as security or strongmen for the company and said Blackfire hasn't even been contacted by local authorities about Abarca Roblero's death, which he called a tragedy.

"The authorities won't talk to us in regards to the investigation," he said. "They're investigating a crime and they're moving forward to find a resolution to this thing."

Family and supporters of Abarca Roblero had requested a meeting with the Governor General, but Minister of State for Foreign Affairs Peter Kent, who was also on the trip, said it was impossible to schedule.

"The program has been set up and pretty finely engineered over the past several months with regards to the Governor General," Kent said. "I think that the time schedule simply being what it was, it didn't work out."