Canada's largest newspaper group is on the auction block amid the biggest upheaval in the country's media industry in years.

CanWest Global Communications Corp., whose late founder Israel (Izzy) Asper once dreamed of creating a worldwide media empire, put most of its big-city dailies into bankruptcy protection Friday after sinking under about $3 billion of debt.

The move ends almost a decade of efforts by the Asper family to make many of Canada's leading newspapers a key part of their drive to turn what was once a small, Winnipeg-based company into a national powerhouse, influencing opinion across the country and beyond.

CanWest said its newspapers – including the National Post, its only daily not now under protection from creditors – are looking for new owners in hopes of wiping out some of the company's debt while keeping the newspapers in business.

The long-anticipated filing for a court-supervised restructuring comes as the newspaper industry undergoes wrenching changes. Advertising revenue is beginning to recover after the recession, but the move by readers and advertisers to the Internet remains a major challenge for the industry.

"It's a sad day for me. The Aspers have lost control of Izzy's legacy," said Ray Heard, a longtime Asper family adviser. Izzy Asper died in 2003, leaving his son Leonard in charge as CanWest's CEO.

The company hopes to fetch between $1 billion and $1.5 billion for the newspaper group – less than half what it paid Conrad Black's Hollinger group for it in 2000.

Last October, CanWest took many of its broadcasting properties, including Global TV, into bankruptcy protection.

The Aspers intend to retain control of their broadcasting business, the foundation of the family's shrinking empire, but they are likely to have little role in the future newspaper company.