If Malaysian authorities thought the disclosure of more information about missing Malaysian Airlines flight 370 would earn them credit with China, they were mistaken.

In an editorial brimming with reproach and frustration, China's official Xinhua news agency accused the Malaysian government of "dereliction of duty," calling the Southeast Asian nation's failure to release information more fully and quickly "intolerable." It also took a swipe at the United States, saying it should be more forthcoming about...