The Alberta Utilities Commission has ruled that TransAlta Corp. deliberately timed outages at power plants during peak times to drive up electricity prices

An investigation was launched after the province’s market surveillance administrator accused the Calgary-based company of manipulating the electricity market by shutting down power plants in 2010 and 2011, when demand was high, in order to drive up power costs.

"The commission concludes, based upon clear, cogent and convincing evidence that TransAlta could have deferred each of the above described outages to off peak hours but chose instead to take them during peak or super-peak hours so as to maximize the benefit to its own portfolio," the commission said in its decision.

However, the commission ruled that the market surveillance administrator did not prove allegations that TransAlta's compliance policies, practices and oversight were inadequate and deficient.

TransAlta has denied all of the allegations, calling them "categorically false."

A spokesperson for the Minister of Energy released a statement to CTV News on the AUC decision saying…

Alberta families need to know that they can get the power they need at a reasonable price. We are very concerned that TransAlta was found to be breaking the rules. When the process is complete, we will take a good look at what happened, as well as what has happened since to determine whether there are steps our government should take to better protect consumers.

The commission says it will determine what penalties will be imposed against TransAlta at a later date.

(With files from The Canadian Press)