The RCMP have released a series of images that they hope will lead to a break in the investigation into three recent explosions at EnCana natural gas facilities near Dawson Creek in northeastern B.C.

The images, taken from video surveillance tapes, show eight people at the Shoppers Drug Mart in Dawson Creek, including some apparently mailing letters at the Canada Post counter inside the store, on Oct. 7.

On that day, three threatening letters were mailed from the drugstore, RCMP Sgt. Tim Shields said Wednesday.

"These letters contained a threatening handwritten message that was sent to the Coffee Talk Express in Chetwynd, the Dawson Creek Daily News and the EnCana Corp. The message demanded that EnCana cease all operations in the Tomslake area by Oct. 11," said Shields.

The letter called EnCana, which is based in Calgary, and other energy companies "terrorists" and gave the companies a deadline to shut down their operations.

RCMP said blasts that occurred on Oct. 11, Oct. 16, and Oct. 31 were deliberately set to damage EnCana's sour gas pipelines.

The investigators want to talk to the individuals who appear in the photographs because they may be able to provide information that could assist the investigation.

"Investigators need to speak with these people. If you are one of these people, or you know the identity of someone in these photographs, please contact the tip line at 1-866-994-7473, or call Crime Stoppers at 1-800-822-TIPS," said Shields.

No suspects, no arrests so far

Police have also created a website with images and other information related to the case.

Police have not said if they have any suspects, but they have not made any arrests.

Meanwhile, EnCana has set up a special phone line and has appealed to the attackers to call and air their grievances.

"We do not believe you intend for the loss of life, however you must understand continuation with these actions significantly, dramatically increases the potential of that occurring," company spokesman Mike McAllister said at a news conference Wednesday.

"It is apparent from your letter you have grave concerns for the course of energy development in the Tomslake area. I urge you to contact EnCana and discuss those concerns with us directly," he said.

With files from the Canadian Press