Chicago ? Boeing Co. took out full-page ads in several newspapers Monday to acknowledge that some of its employees used privileged documents from rival aerospace company Lockheed Martin to win a $1.88 billion federal rocket contract.

The Air Force and Justice Department have been investigating Boeing’s use of the documents in its successful bid for the 1999 contract.

In a letter in The New York Times, The Wall Street Journal, The Washington Post, The Washington Times and Roll Call, Boeing Chairman and Chief Executive Phil Condit said the “actions of a handful of people” did not represent the company’s ethics.

“It has become clear that some of our employees did not behave properly,” Condit said.

Boeing was battling Lockheed Martin for the right to build rockets for spy, communications or other satellites. Boeing hired a former Lockheed Martin employee and now acknowledges the employee brought private Lockheed Martin documents to help Boeing bolster its case.

“Boeing has worked very hard to justify its reputation,” Condit said in the letter. “However, we are a large organization, and we are not always perfect. Despite all of the guidance and training we give every one of our employees, there have been mistakes.”

The Chicago-based company previously fired two employees from its Huntington Beach, Calif., operations and disciplined a third.

Aerospace industry analyst Paul Nisbet said Boeing’s public-relations bid was unusual.

“It seems to me you’re probably bringing more attention to the situation than would otherwise be the case,” Nisbet said.

Nisbet said he doubted there would be any serious ramifications to the aerospace giant. The government could impose a relatively modest fine, such as the $111 million that Northrop Grumman Corp. announced Monday it would pay for overcharges on federal contracts.

“It’s virtually impossible to suspend a major contractor like Boeing,” Nisbet said.