The Chinese government is developing detailed profiles of U.S. workers and private citizens as part of a long-term strategic espionage campaign that might include blackmailing key government officials, said the chairman of the House Homeland Security Committee.

The theft of data on as many as 4 million government workers disclosed last week was done by the same Chinese hackers who stole tens of millions of health care records in recent attacks on Anthem Inc. and Premera Blue Cross, said Rep. Michael McCaul, a Texas Republican.

"It's a huge intelligence collection operation," McCaul said in a phone interview Monday. "The fact that they're able to do this now and sweep it up shows that China is becoming more sophisticated."