Dwight Duncan said Friday the planned shutdown of two coal-fired power plants over pollution concerns will have to be delayed.

Ontario's Energy Minister based the decision on what he called a "disappointing" change in the power forecasts for the next few years.

The Liberals had promised during the 2003 election campaign to close all the coal-fired plants by 2007, but had already pushed that projection for at least two of the four back to 2009.

These further changes mean the Lambton plant near Sarnia and the Nanticoke facility in southwestern Ontario will now stay open longer than planned. But Duncan would not give any estimate of how long that might be.

Two other plants, in Thunder Bay and Atikokan, are still scheduled to close next year, while the giant Lakeview facility in Etobicoke has already closed and will be demolished this Monday.

Terry Young of the Independent Electricity Market Operator, says the coal generators are needed because of changes in the agency's forecast, which predicts less supply and more demand than previously thought.

"Given the increasing impact of the weather on the electricity demand, more and more people are turning to air conditioning and we are seeing very high demands for electricity," he said.

"Given that, and given when you get into the hot summer you see drought-like conditions often, and that impacts the amount of resources you have to meet that demand."

The IEMO was expected to deliver an update Friday afternoon on a report from earlier this year that was to confirm its opinion that the life of the coal plants would have to be extended.