The U.S. Department of Labor said Wednesday it ordered Bank of America Corp. to rehire and pay $930,000 to an employee improperly fired in a whistleblower case.

The worker reported "pervasive wire, mail and bank fraud" involving employees at Countrywide Financial Corp., the mortgage lender acquired by Bank of America in July 2008, the government said. The bank was ordered to pay back wages, damages and attorneys' fees.

"It's clear from our investigation that Bank of America used illegal retaliatory tactics against this employee," said David Michaels, assistant secretary of the Labor Department's Occupational Safety and Health Administration. "This employee showed great courage reporting potential fraud and standing up for the rights of other employees to do the same."

The Los Angeles-area employee, whose name wasn't disclosed, was fired shortly after the Countrywide acquisition became final, the government said.

The employee led and participated in internal investigations at Countrywide in 2007 and 2008 that revealed "various types of document forgery to manipulate borrowers' assets and income," a Labor Department spokeswoman said. The employee also voiced concerns about retaliation against Countrywide employees who reported fraud, according to the Labor Department.

The agency said Countrywide's investigation of the employee started before the Bank of America merger and continued after it was completed. The Labor Department spokeswoman said the company retaliated due to the employee's "reports of fraud and retaliation against other employees."

Bank of America said in a statement that it is "disappointed with the ruling and plans to exercise our option to challenge the order." The bank said its decision to fire the employee was "solely based on issues with the employee's management style and in no way related to the employee's complaints and the allegations made in the complaint."

Bank of America has faced mounting troubles related to the bank's acquisitions of Countrywide Financial. in 2008 and Merrill Lynch & Co. in 2009. The Charlotte, N.C.-based bank has faced numerous lawsuits from private investors and the federal government, alleging that the bank failed to fully disclose the risks of mortgage-backed bonds sold to investors.

Earlier this year, a criminal probe of Angelo Mozilo, former chief executive at Countrywide, was closed without charges being filed. The investigation was led by the U.S. Attorney's office in Los Angeles. Last year, Mr. Mozilo agreed to pay $67.5 million to settle civil-fraud charges filed against him by the Securities and Exchange Commission.