MONCTON, N.B. -- A group opposed to shale gas development in New Brunswick is raising questions about the RCMP's enforcement of an injunction against protesters last week in the province that turned violent.

Jim Emberger, of the New Brunswick Anti-Shale Gas Alliance, says the Mounties should be asked about their use of force Thursday near Rexton.

"There remain many questions about the authorization, timing, necessity and execution of this action and the shocking escalation in the use of force," he said Tuesday at a news conference in Moncton, N.B.

Emberger said there had been many peaceful anti-shale demonstrations in the province over the last two years and questions must be answered to determine why Rexton was different.

"Leaving them unanswered will set a precedent that will guarantee a recurrence of Rexton in the future," he said.

Forty people were arrested and weapons including guns and improvised explosive devices were seized when the Mounties enforced the court-ordered injunction to end the blockade of a SWN Resources storage compound for exploration equipment and vehicles.

Six police vehicles including an unmarked van were burned. The RCMP said they had Molotov cocktails tossed at them, and in response they fired non-lethal beanbag-type bullets and used pepper spray to defuse the situation.

Assistant commissioner Roger Brown, the RCMP's commanding officer in the province, has defended the police response, saying officers acted because they grew concerned that public safety was at risk.

The RCMP blocked Route 134 three weeks ago after protesters began spilling onto the road. Protesters then cut down trees and placed them across another part of the road, blocking the entrance to SWN's equipment compound.

The company has said it's only in the early stages of exploration in New Brunswick.

Emberger also points blame at the provincial government, saying an honest and open discussion with the public about shale gas could have prevented the clash in Rexton from happening.

Premier David Alward's office has said he is expected to meet with members of the Elsipogtog First Nation, some of whom were arrested when the injunction was enforced, some time this week.

Emberger said the alliance -- which represents community groups opposed to shale gas exploration -- will track the position of candidates on the shale gas issue in next year's provincial election.