Investigators say the Boeing 777 was deliberately diverted during its overnight flight and flew off-course for hours. Investigators have refused to rule out hijacking, sabotage or pilot suicide for the plane's disappearance and were last night continuing to check the backgrounds of all 227 passengers and 12 crew members - in addition to the ground crew - for personal problems, psychological issues or links to terrorists.

Despite the ongoing probe, the Chinese ambassador to Malaysia Huang Huikang this morning told a press conference that China can "rule out the suspicion of any Chinese passengers engaging in terrorist or sabotage activities on board the MH370 flight".

China "conducted meticulous investigation into all the (Chinese) passengers, and did not find any evidence for sabotaging activity," Chinese state broadcaster CCTV quoted Huang as saying.

Malaysian Defense Minister Hishammuddin Hussein said last night that finding the plane was still the main focus, and he did not rule out that it might be discovered intact.

“The fact that there was no distress signal, no ransom notes, no parties claiming responsibility, there is always hope,” Hishammuddin said at a news conference.

Malaysian Airlines CEO Ahmad Jauhari Yahya said yesterday that an initial investigation indicated that the last words ground controllers heard from the plane - “All right, good night” - were spoken by the co-pilot, Fariq Abdul Hamid.

A voice other than that of Fariq or the pilot, Zaharie Ahmad Shah, would have been clearest indication yet of something amiss in the cockpit before the flight went off-course.

Malaysian officials had earlier said that the words came after one of the jetliner’s data communications systems — the Aircraft Communications Addressing and Reporting System (ACARS) — had been switched off, suggesting the voice from the cockpit may have been trying to deceive ground controllers.

However, Ahmad said that while the last data transmission from ACARS — which transmits plane performance and maintenance information — came before that, it was still unclear at what point the system was switched off, making any implications of the timing murkier.

The new information opened the possibility that both ACARS and the plane’s transponders, which make the plane visible to civilian air traffic controllers, were turned off at about the same time. It also suggests that the message delivered from the cockpit could have preceded any of the severed communications.

Malaysia yesterday appealed for help from countries with radar and satellite data, as Australia, China, Indonesia and Kazakhstan deployed military and civilian resources.

Twenty-six countries were scouring sea and land for the Boeing 777 aircraft that disappeared 10 days ago with 239 people, 154 of them Chinese, on board.

"For countries in search corridors, we are requesting radar and satellite information, as well as specific assets for the search and rescue operation," Malaysia's acting transport minister, Hishammuddin Hussein, said. "We are asking them to share their land, sea and aerial search and rescue action plans with the Rescue Coordination Centre here in Malaysia, so that we can coordinate the search effort."

Watch: MH370 Captain and co-pilot last time on camera

Chinese Premier Li Keqiang asked during a phone call with Malaysian Prime Minister Najib Razak that Malaysian officials provide more detailed and accurate information and better coordinate with all parties, according to the Chinese government website.

China has merchant ships, as well as other vessels, involved in the search and has mobilised additional planes and 21 satellites. Australia has dispatched three additional military aircraft, and the US has sent one more aircraft to join the search. French investigators joined Chinese aviation officials to work with Malaysia Airlines and the nation's Department of Civil Aviation.

At least one aviation expert called the scope of the search without equal in terms of area, the number of personnel and equipment deployed, and the number of countries directly or indirectly involved.

"As far as we know the scale of the search for MH370 is indeed unprecedented,'' said Harro Ranter, president of Aviation Safety Network, a non-profit group that tracks aircraft accidents. "Searches may have lasted a long period of time - like Air France 447 [in 2009] and an Adam Air B737 in 2007 - but search parties did have a broad idea of where to look since debris had been located."

Watch: Last words from missing Malaysian jet spoken by co-pilot

After more than a week of anger and confusion voiced by passengers' families who have faulted the accuracy of information shared by officials, Malaysian authorities said the country had been co-operating with the FBI, Interpol, and other international law-enforcement agencies since day one.

"Our priority has always been to find the aircraft," Hishammuddin said. "But we also have a responsibility not to release information until it has been verified by the international investigations team. It would be irresponsible to deploy substantial assets merely on the basis of unverified and uncorroborated information."

On Sunday, Najib called off the week-long search for wreckage in the South China Sea and other areas on MH370's scheduled flight path after satellite data showed that the plane had turned sharply westward. Najib called the plane's disappearance a "deliberate act".

Suspicion has fallen on the pilots because of their aviation experience. Investigators have not ruled out hijacking, sabotage, pilot suicide or mass murder, and are checking the backgrounds of all 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.

Hands on the deck

Twenty-six countries are now involved in the massive international search for the Malaysia Airlines jet that disappeared on March 8 with 239 people on board. They include not just military assets on land, at sea and in the air, but also investigators and the specific support and assistance requested by Malaysia, such as radar and satellite information.

Here’s a look at major countries and their response:

MALAYSIA

Malaysia, which is co-ordinating the search, has deployed about 18 aircraft and 27 ships, including the submarine support vessel MV Mega Bakti, which can detect objects at a depth of up to 1,000 metres.

AUSTRALIA

Australia has sent two AP-3C Orion aircraft, one of which is searching the waters to the north and west of the Cocos Islands in the southern Indian Ocean, and plans to deploy two more. Prime Minister Tony Abbott said that all Australian agencies “are scouring their data to see if there’s anything they can add to the understanding of this mystery”.

CHINA

An official with the Chinese Civil Aviation Authority says the missing plane did not enter Chinese airspace. The Chinese defence ministry and foreign ministry didn’t immediately respond to questions on radar information. China has deployed nine navy ships and civilian patrol vessels and a variety of fixed-wing and rotary aircraft, along with a team of experts dispatched to Malaysia.

UNITED STATES

A P-8A Poseidon, the most advanced long-range antisubmarine and anti-surface warfare aircraft in the world, has been searching the Indian Ocean. The US Navy has also deployed the destroyer USS Kidd with two MH-60R helicopters.

INDONESIA

Indonesian Air Force spokesman Hadi Tjahjanto says military radars on Sumatra Island found no trace of the jet and that data requested by the Malaysian government has been handed over. He says that search efforts have shifted from the Strait of Malacca to the corridor stretching from northern Sumatra to the Indian Ocean.

PAKISTAN

The head of the Pakistan Civil Aviation Authoritysays radar recordings shared with Malaysia found no sign of the jet. INDIA India put its search operations in the Andaman Sea and the Bay of Bengal on hold at weekend but continues to coordinate with Malaysia about possible new search areas.

OTHERS

Other nations involved are Thailand, Bangladesh, Brunei, France, Japan, Kazakhstan, Kyrgyzstan, Laos, Myanmar, New Zealand, the Philippines, Russia, Singapore, South Korea, Turkmenistan, United Arab Emirates, Britain, Uzbekistan and Vietnam.

Associated Press