Hereditary chiefs from the five clans of the Wet'suwet'en people, who oppose the project, have been trying for more than a year to force a halt to work in the north of the province.

Coastal, which is owned by private equity firm KKR & Co Inc, Alberta Investment Management Corp and TC, says it is allowed to work on the pipeline, citing an injunction granted by the British Columbia Supreme Court in 2019 against blockades preventing access for workers. It says the protests are illegal.

Coastal GasLink said in a statement on its website on Monday that it was concerned for the safety of its workers after forestry roads leading to their housing lodges were blockaded.

Trees were felled, and project vehicles and equipment have been vandalized in the area, Coastal said.

The C$6.6 billion pipeline will move natural gas from northeast British Columbia to the Pacific coast to feed the LNG Canada export terminal, which is under construction by Royal Dutch Shell and its partners. Some 28% of the 670-km (420-mile) route passes through Wet'suwet'en lands.

In a statement on Sunday, one of the clans, the Gidimt'en, said it had demanded Coastal GasLink employees leave the area. The company said that it had made "multiple efforts" seeking dialogue but had not received any response.

No one at the Gidimt'en or the Royal Canadian Mounted Police was immediately available to comment on Monday.

The dispute poses a potential challenge for Prime Minister Justin Trudeau, who has made reconciliation with Canada's marginalized aboriginal population a priority. He also says Canada will rely on fossil fuels for decades to come, however.

All of the elected indigenous band councils along Coastal GasLink's route support the project. But Wet'suwet'en hereditary chiefs oppose it and say they, not the community's elected officials, hold authority over traditional lands.

"The Wet'suwet'en hereditary chiefs have never ceded, surrendered, or lost in war, title to this territory. That means that what they say goes," a spokesman said in a statement.

(Reporting by David Ljunggren in Ottawa and additional reporting by Ismail Shakil in Bengaluru; Editing by Andrea Ricci and Dan Grebler)