As the search operation entered the third week, the prime minister said his thoughts and prayers were always with the families of the passengers and crew of the Boeing 777-200ER aircraft that vanished on March 8.
"As we enter the third week in the search for MH370, be assured that the Malaysian government is fully committed to the search operation and we will not stop until the plane is found," he said in his latest Facebook posting.
Najib also expressed his appreciation to the Australian government and other countries taking part in the search for the plane.
"I would like to take this opportunity to convey my gratitude to the Australian government and other nations involved for their tireless efforts in locating our missing plane," he said.
The plane with 239 passengers and crew onboard, went missing about an hour into its Kuala Lumpur-Beijing flight after taking off from the Kuala Lumpur International Airport at 12.41am.
Najib announced on March 24 that Flight MH370 had ended in a remote region of the southern Indian Ocean.