KUALA LUMPUR, Malaysia — When a Chinese government vessel took the world by surprise this month with its announcement that it had detected underwater signals that might have come from the missing Malaysia Airlines plane, China suddenly looked like the hero of the multinational search effort.

Within days, however, the Chinese claims were discounted, and attention shifted to another set of signals recorded by American personnel aboard an Australian ship hundreds of miles away.

Still, the Chinese claims have exasperated some officials from the United States and other participating countries. The announcement was only one in a series of moves by China that might have been intended to project competence, according to officials and analysts, but only served to distract and delay the search effort.

“Everybody wants to find the plane,” said a senior Defense Department official who spoke on the condition of anonymity because he did not want to appear overly critical of the Chinese. But, he continued, “false leads slow down the investigation.”