The Sierra Club of Canada is joining demands for a public inquiry into spying by Alberta's energy and utilities regulator.

CBC News first reported in June that the Alberta Energy and Utilities Board hired private investigators to monitor landowners opposed to a controversial power line.

A government report released Monday called the energy board's tactics "repulsive," referring to private investigators who posed as landowners and listened in on conference calls made by the landowners and their lawyers. Alberta's privacy commissioner has already ruled the board broke provincial laws.

'They were all entrusted with the public good here and they failed.'— Joe Anglin, head of landowners group

The Sierra Club said Tuesday that it wants to know what information may have been collected, and where that information has gone. It added that the energy board's actions have raised questions about other controversial energy projects.

Alberta Energy Minister Mel Knight said Monday that the board's use of undercover investigators was wrong. As directed by the report, a written security policy will be put in place, he said.

But Joe Anglin, the head of the landowners group that first made the spying allegations, called the latest report a "whitewash" because no one was held accountable.

"Quite honestly, as the person in charge, Mel Knight should step down voluntarily from his cabinet position and the EUB board members should be fired or they should step down voluntarily because they were all entrusted with the public good here and they failed," Anglin said.

The Alberta Liberals and the NDP are calling for both a public inquiry and the resignations of Knight and the eight-member board. Knight said he sees no reason for an inquiry.

The landowners have launched a series of legal challenges of both the public hearing process and the proposed power line.