United Airlines Flight 934 to Heathrow was searched at a searched at a secure area of Los Angeles International Airport before taking off about 15 minutes behind schedule Saturday.
The delay was caused by an anonymous telephone caller claiming there was a bomb aboard the plane, the newspaper said. A similar call two weeks ago also specified Flight 934.
Law enforcement sources told the Times the first threat had been traced to a male voice using a New York City pay phone. Saturday's incident involved an apparent female calling from a pay phone in Las Vegas.