The United States said Monday that it has no "independent corroboration" about the announced crash of the missing Malaysian jetliner in the southern Indian Ocean.

"I don't have any independent corroboration of that," State Department spokeswoman Marie Harf told reporters at a regular news briefing, hours after Malaysian Prime Minister Najib Razak announced the jet's crash at a press conference citing new analysis of satellite data.

"I have no reason to believe it's not true. I just don't have any update for you," Harf said, adding Washington was working " very closely" with the Malaysian government.

Najib said the missing Malaysia Airlines Flight MH370's last position was in the middle of the Indian Ocean, west of Perth, Australia.

The Boeing 777-200 aircraft, en route from Kuala Lumpur, capital of Malaysia, to Beijing, with 227 passengers and 12 crew members aboard, mysteriously disappeared from radar shortly after takeoff in the early hours of March 8.