MEXICO CITY - Dozens of people protesting the killing of an anti-mining activist demonstrated outside the Canadian embassy on Thursday, blaming the death on a Canadian-owned mining company operating in southern Chiapas state.

Supporters of the Mexican Network of People Affected by Mines claim employees of a mine owned by Calgary-based Blackfire Exploration Ltd. were involved in the shooting death of activist Mariano Abarca Friday.

Blackfire has denied the company had any involvement in the killing.

Fellow activists said Abarca's death had been foretold.

"They had threatened him, they had beaten him, and the only thing left for them was to kill Mariano, they had said that, and the authorities knew it," said Gustavo Castro.

Abarca long opposed the mine. But in September he upped the stakes in the battle when he led other residents of the township of Chicomuselo, near the Guatemalan border, in blocking an access road to the open-pit mine where Blackfire extracts barite, a nonmetallic mineral used in oil drilling projects.

The blockade was intended to press demands for 3 million pesos ($235,000) that residents of a nearby hamlet say they were owed for ore taken from land outside the company's concession area.

With jobs at stake, the conflict grew heated.

Castro alleged that mine employees had come to Abarca's house, beaten him and his children, and threatened to kill him.

Requests for comment from the company Thursday were not immediately answered.

Police in Chiapas are still investigating the drive-by shooting, in which a man on a motorcycle riddled Abarca with bullets as he sat in a vehicle near his home in Chicomuselo.

Demonstrators at the protest outside the embassy Thursday held banners reading "Justice!" and "Transnationals out!"

Luz Perez Torres, 38, a Chicomuselo homemaker and mother of two, said the mine had tainted local water supplies, preventing residents from using local streams for fishing or bathing.

"We get welts on our skin from the water," she said.

Abarca's death, she said, was the last straw: mine opponents are now demanding the company withdraw from Chiapas.

The southern state of Chiapas, rich in oil and gas, was opened to mining concessions about 10 years ago by the federal government. The leases, mostly held by Canadian firms, have been challenged by residents who are concerned about environmental damage and say they have a right to the land.