CALGARY - The Ontario Securities Commission says it will hear an application on Friday in Toronto by activist U.S. investors who want to delay the annual meeting of power utility TransAlta Corp. (TA.TO) and impose a transaction vote.

The regulator says its proceeding will consider the application of Mangrove Partners, which with entities affiliated with Bluescape Energy Partners owns 10 per cent of TransAlta's shares, to delay the meeting from April 26 until at least June 1.

The American shareholders also want the regulator to force TransAlta to hold a vote on its proposed deal with Brookfield Renewable Partners, under which $750 million would be invested in the company's hydroelectric assets.

The arrangement is now conditional on shareholders voting for two director nominees from Brookfield at the annual meeting but the U.S. firms want a vote on the deal itself by shareholders not having an interest in the transaction.

The U.S. investors say the Brookfield deal was "rushed" and prevents TransAlta from looking at potential better options.

In an interview with BNN Bloomberg, TransAlta Chairman Gordon Giffin blasted Mangrove’s demands on its deal with Brookfield.

“I have every confidence in the regulatory process in Canada, that the regulators in Alberta and Ontario – whoever ends up making judgments on this – will do it in a rational way,” Giffin said Wednesday. “I do not think, frankly, these folks in New York and Texas even understand the regulatory process in Canada.”

Analyst Jeremy Rosenfield of Industrial Alliance Securities says in a report Wednesday that he doesn't see better options for TransAlta but adds there are "merits" to a slower and more transparent conversation on its strategic initiatives.

With files from BNN Bloomberg