Alberta's arms-length energy regulator hired a private investigator to pose as a concerned citizen and infiltrate a group of landowners opposing the construction of a massive power line, new documents show.

The provincial NDP released documents obtained under Freedom of Information legislation Thursday that also show investigators gave the Energy and Utilities Board passwords that would allow it to listen in on the landowners' private conference calls.

'We only had a bunch of grandmothers there and the big 250-pound guy in the middle eating all the cookies was the ex-RCMP cop.'—Joe Anglin

NDP leader Brian Mason said it is a case of using public money to spy on Albertans.

"This goes far beyond what's necessary to protect the integrity of the hearing," Mason said.

"This was intelligence gathering and it was political intelligence."

Landowner Joe Anglin called the documents "a huge vindication."

"The way we found these guys out is almost comical. We only had a bunch of grandmothers there and the big 250-pound guy in the middle eating all the cookies was the ex-RCMP cop."

A spokesman for the board said the energy regulator would issue a release in response to the documents, but minutes later said there wasn't going to be a press release.

The Alberta Energy and Utilities Board admitted in June to hiring "security personnel" to oversee central Alberta landowners opposed to a proposed 500-kilovolt power line between Calgary and Edmonton.

Residents worry about health effects

Landowners living near the proposed route are concerned about possible health effects and have complained the board has already decided on approval.

In April, board staff said they were physically threatened in three incidents at a public hearing into the project. Afterward, the board decided to accept only written submissions and close the courtroom in the central Alberta town of Rimbey.

Landowners were moved into a nearby recreation centre to watch the proceedings on TV.

Board spokesman Davis Sheremata said in June the energy regulator had hired security officers to keep an eye on the landowners watching the hearings in the recreation centre.

The landowners said the private investigators were actually spies and their lawyer called for the hearings to be restarted.