WILMINGTON, Del. -- The chief financial officer for the Tribune Co. is defending proposed bonuses of up to $70 million for the company's top managers.

Chandler Bigelow III told a federal bankruptcy court in Delaware on Friday that Tribune wants to motivate key managers working in a difficult media environment and trying to emerge from Chapter 11.

But a union representing employees of Tribune's Baltimore newspaper, The Sun, says the bonuses are unwarranted. It is joined in its objection by three other unions.

Tribune, which also owns the Los Angeles Times, Chicago Tribune and other dailies, along with 23 TV stations, filed for bankruptcy protection in December because of dwindling advertising revenues and $13 billion in debt. Much of the debt was amassed when Sam Zell took the company private in 2007.