Screeners at Newark Liberty International Airport failed 20 of 22 security tests conducted by undercover U.S. agents last week, missing an array of concealed bombs and guns at checkpoints throughout the hub's three terminals, federal security officials familiar with the results said.

The tests, conducted Oct. 19 by U.S. Transportation Security Administration "Red Team" agents, also revealed significant failures by screeners to follow standard operating procedures while checking passengers and their baggage for prohibited items, said the officials, who spoke on condition of anonymity because it is against TSA policy to release covert-test results.