Investigators looking into the crash of a China Eastern Airlines jet are examining whether it was due to intentional action on the flight deck, with no evidence found of a technical malfunction, two people briefed on the matter said.

The Wall Street Journal reported on Tuesday that flight data from one of the Boeing 737-800's black boxes indicated that someone in the cockpit intentionally crashed the plane, citing people familiar with the preliminary assessment of U.S. officials.

Boeing, the maker of the jet, and the U.S. National Transportation Safety Board (NTSB) declined to comment and referred questions to Chinese regulators.