Director-General Datuk Azhauruddin Abdul Rahman said authorities confirmed the objects found in the Gulf of Thailand did not match the missing aircraft.
Malaysia Airlines Flight MH370, carrying 227 passengers and 12 crew, disappeared over the South China Sea about an hour after departing for Beijing from Kuala Lumpur, Malaysia.
Azhauruddin said the possibility of a hijacking remains under consideration but said the priority is locating the plane, the newspaper Malaysia Star reported.
Acting Transport Minister Datuk Seri Hishammuddin Tun Hussein said the search-and-rescue operation was expanded on speculation the airplane may have turned back to the originating airport for some mechanical reason.
Viet Nam News reported the Boeing 777 lost contact with an air traffic control tower about 120 nautical miles southwest of Vietnam's Ca Mau cape and 25 nautical miles south of the Vietnam-Malaysia maritime border. Vietnam, Malaysia, the Philippines, China and the United States contributed planes and ships to participate in the search.
Concerning a report that four passengers with stolen passports were on the flight, Hishammuddin said, the names had been forwarded to Malaysian and international intelligence agencies.
Hishammuddin stressed it hasn't been confirmed that there was a security risk and authorities are investigating the entire passenger list.
In Washington, the National Transportation Safety Board said in a statement it sent a team of investigators to Asia to help assist with the investigation. The team was accompanied by technical advisers from Boeing and the Federal Aviation Administration.