A saboteur's bomb blast on Oct. 12, 2008, created a 1.8-metre-wide crater near an EnCana natural gas pipeline about 50 kilometres east of Dawson Creek in northern B.C. A sixth explosion, causing a small gas leak, was reported Saturday. (RCMP)

RCMP are asking residents in northeastern B.C. to be patient as they investigate the sixth bombing of an EnCana Corp. natural gas pipeline, attacks they are now labelling "domestic terrorism."

The latest attack was discovered Saturday near the small village of Pouce Coupe, eight kilometres south of Dawson Creek, just three days after the fifth explosion. The latest blast caused a small leak of sour gas that was quickly contained.

RCMP Cpl. Dan Moskaluk said he understands the public might be frustrated that the attacks are continuing, with the bomber still free.

"But we want to assure the public that the resources that are being put to this string of incidents are quite substantial," he said.

No new leads in months

In October, someone sent a handwritten letter to local media outlets demanding a stop to oil and gas operations in the area, calling EnCana and other companies "terrorists" that are "endangering our families with crazy expansion of deadly gas wells."

The note was followed by three successive explosions, two of which caused leaks of sour gas, which contains toxic hydrogen sulphide.

In January, a fourth bombing destroyed a metering shed at a wellhead near the community of Tomslake.

The RCMP's anti-terrorism unit has been investigating, but police haven't announced any substantial leads since last December, when they released eight surveillance photos that apparently turned out to be a dead end.

Moskaluk said that doesn't mean investigators haven't made progress, but he declined to elaborate.

"I can't quantify that," said Moskaluk when asked whether there have been any other substantial leads since the surveillance photos.

"The guys are in the trenches and they're working away on the physical scene. We have a multitude of other specialty units and resources that are attached to this investigation."

Bomber likely from the area

RCMP say they believe the bomber is from the local area and has a grievance with EnCana, which has offered a $500,000 reward for information in the case.

Terrorism expert Paul Joosse said the renewed bombings might be an attempt to get the bomber's original grievances — apparently outlined in the October letter — back in the news.

Joosse, who teaches at the University of Alberta, said it's significant that the RCMP are now referring to the attacks as terrorism, a term the force has largely shied away from, preferring instead to call them "vandalism."

While the force said the change simply reflects the growing threat that's emerging after six attacks, Joosse suggested it might be a way to encourage more co-operation from the public.

The RCMP suggested in the past that there are people in the area who likely have information about the bombings but are keeping quiet.