"As per normal procedure, the Royal Malaysian Police are investigating all crew and passengers on board Flight MH370, as well as engineers," Acting Transport Minister Hishammuddin Hussein in a statement Sunday.
The plane disappeared about an hour into a flight from Kuala Lumpur to Beijing March 8; the fate of the 227 passengers and 12 crew members still is unknown.
Hishammuddin said search and rescue teams were working with 15 countries to locate the missing aircraft, Bernama reported.
"Malaysian officials are currently discussing with all partners how best to deploy assets along the two corridors," said Hishammuddin.
Malaysian Prime Minister Datuk Seri Najib Tun Razak said Saturday evidence showed the plane's communications system was deliberately disabled by someone aboard the flight, Bernama said.
Authorities are working to locate the plane and are seeking satellite data from other countries for any sign of where Flight 370 may have gone after it deviated from its course, he said.
"Our primary motivation has always been to find the plane. Over the last seven days, we have followed every lead and looked into every possibility," Najib said.
"For the families and friends of those involved, we hope this new information brings us one step closer to finding the plane. We realize this is an excruciating time for the families of those on board. No words can describe the pain they must be going through. Our thoughts and our prayers are with them," he said.
A U.S. official told CNN U.S. intelligence teams believe "those in the cockpit" were responsible for the plane's disappearance.
The official's comments came after Malaysian authorities searched the home of the lead pilot Saturday.
"The Malaysians don't do this lightly," the official, who spoke on condition of anonymity, said Saturday.
However, other theories, including the possibility of hijackers, have not been ruled out, the official said.