Authorities on Sunday said the search area for the missing Malaysia Airlines jet had been "significantly expanded," and that the number of countries involved in the hunt for the aircraft had increased from 14 to 25.
"The search area has been significantly expanded and the nature of the search has changed from focusing mainly on shallow seas," Malaysian transport minister Hishamuddin Hussein said at a press briefing in Malaysia's capital Kuala Lumpur.
"We are now looking at large tracts of land crossing 11 countries as well as deep and remote oceans," he added, saying the operation was in "a new phase."
According to Hussein, Malaysia Airlines said the pilot and co-pilot did not specifically request to fly together on flight MH370, which vanished eight days ago.
Police confirmed earlier that they had searched the homes of both pilot Zahari Ahmad Shah and co-pilot Fariq Ab Hamid on Saturday, and had removed the pilot's personal flight simulator for investigation.
Speaking at the same news conference Sunday, Malaysia's Inspector General Khalid Abu Bakar said the investigation had officially been reclassified to include hijacking, sabotage, terrorism and "all offenses under [the] aviation offenses act."
"So that covers everything. So that means that we are intensifying our investigation," he said. "But the focus remains the same."
Authorities repeatedly said that they were investigating all crew, passengers and any ground staff who may have had contact with the Boeing 777 before take-off, and were not focusing on any specific person or people.
On Saturday, Malaysian Prime Minister Najib Razak announced the biggest break in the investigation so far, revealing that the plane was deliberately diverted off course. He stopped short of calling it a hijacking, however.
This is a breaking news story. Please check again for more updates.
-NBC News' Emma Ong contributed to this report
First published March 16 2014, 2:57 AM