The Wall Street Journal says the March crash of a China Eastern Airlines plane may have been intentional.

The Boeing 737-800 crashed into a mountain in the Guangxi Zhuang Autonomous Region in southern China on March 21. All 132 people on board died.

The US newspaper on Tuesday quoted sources familiar with US officials' preliminary assessment. It says that flight data indicates someone in the cockpit intentionally crashed the plane. The paper added their source said US investigators do not have all information available from their Chinese counterparts.

Boeing officials and US aviation authorities are cooperating with China's investigation.

The passenger jet is believed to have plunged almost vertically from a high altitude. There has been speculation someone deliberately caused the crash.

Chinese aviation authorities said in a summary of a preliminary report in April that the cause of the crash had yet to be determined. They said the plane's black box recorders were severely damaged.

Chinese investigators are continuing their probe.