SYDNEY, May 30 (Xinhua) -- Some family members of passengers on board MH370 are frustrated and want answers after authorities ended the search in an area where underwater pings were detected.

It was first believed the pings were coming from the plane's black box and the discovery in April triggered a 850 square kilometer zone search by underwater vehicle.

The search in the ping zone was called off on Thursday with one U.S. Navy official saying the pings were most likely coming from a ship.

Selamat Osman, whose son was on board MH370, told News Corp Australia Network from his home in Malaysia that he was disappointed in the efforts to find the missing plane.

"I feel really disappointed. The attempt to search for the plane is not optimal yet," Mr Osman said.

"They should be working harder rather than talking and talking. In my opinion, they have too much talking rather than working. It doesn't make us really feel sure about their work.

"I am really disappointed that the search operation hasn't found anything."

Sarah Bjac, whose partner Philip Wood was one of the three Americans on board the plane, represents a group of relatives of passengers frustrated with the search efforts.

"It is a sad commentary on the situation that family members are rejoicing that there is still a chance that our loved ones are being held hostage by hijackers. It is a better option than dead at the bottom of the ocean."

"I've been saying this since the first weeks. We are being managed and intentionally distracted. Lead, redaction, lead, redaction, lead -- until three months later there is not a single solitary fact or piece of evidence that has been proven to be true, not one. Both the leads and the redactions come from a mix of official sources and "leaks". Nothing is logical or consistent or according to standard expected protocols much less common sense."

Oceanographer Dr Erik Van Sebille said it was unfair to blame authorities because deep ocean research was a hard task. "Sounds are made at all different frequencies. The ocean is more a cacophony of these different sounds. You might think you hear one thing but it is another," Dr Van Sebille, from the University of New South Wales said. "I think we should be very careful with our criticism. There is no team in the world that could have done a better job than this. Navies know their sounds in the ocean like nothing else."