Planes searching an area where Chinese satellites spotted possible debris from a missing Malaysian passenger jet have found no sign of wreckage, officials said Thursday, dimming hopes of a breakthrough in the mystery.

China said late Wednesday its satellites had detected three large floating objects in a suspected crash site near where the Malaysia Airlines plane, which disappeared Saturday on a flight from Kuala Lumpur to Beijing with 239 people on board, lost contact.

False alarms, swirling rumors and contradictory statements have made the wait all the more agonizing for the families of the 239 people on board the missing Malaysia Airlines flight MH370.

As the search dragged into its fifth day, here are some of the key areas of confusion:

The search for Malaysia Airlines Flight 370 has rekindled a debate over the iconic "black box" flight recorder and whether it's time for aircraft to start live-streaming in-flight data in real time.

Civil aviation industry sources agree the technology exists for commercial airliners to immediately relay via satellite vital technical information otherwise compiled by a flight data recorder in the course of a flight.

Malaysia faced a storm of criticism Wednesday over contradictions and information gaps in the hunt for a missing airliner with 239 people on board, as the search zone dramatically veered far from the intended flight path.

Efforts to locate Malaysia Airlines flight 370, involving the navies and air forces of multiple nations, had focused on Vietnam's South China Sea coast where it last made contact Saturday on a journey from Kuala Lumpur to Beijing.

Two suspect men who flew on a missing Malaysian airliner appear to have been Iranian illegal immigrants, officials said Tuesday, lessening fears of terrorism but doing little to unlock the agonizing riddle of what has befallen the plane's 239 passengers and crew.

On the fourth day of a multinational search at sea and on land, relatives desperate for news of loved ones aboard Malaysia Airlines MH370 said their hopes for a miracle were ebbing away.

The two mystery passengers who triggered an international terrorism probe into a missing Malaysian jet now appear to be young Iranian migrants seeking a new life overseas, officials said Tuesday.

The case of the pair, who traveled with stolen passports, has focused attention on the murky world of people smuggling, particularly through Southeast Asia, which has long been renowned as a hub of illegal migration and human trafficking.

Beijing is deploying as many as 10 satellites in hopes of tracking down Malaysia Airlines flight MH370, state media reported Tuesday, as the search for the vanished aircraft entered its fourth day.

The high-resolution satellites, which are controlled from the Xian Satellite Control Centre in northern China, will be used for navigation, weather monitoring, communications and other aspects of the search-and-rescue effort, the People's Liberation Army (PLA) Daily said.

Nearly three days after it disappeared while en route from Kuala Lumpur to Beijing, mystery still shrouds the fate of Malaysia Airlines flight MH370 and the 239 people on board.

No debris from the Boeing 777-200ER has been recovered despite an international search involving the navies and air forces of several Asian nations as well as the United States.

Thailand's role as a hub for criminal networks using false documents is in the spotlight after two unknown passengers on vanished flight MH370 used passports stolen in the kingdom, sparking fears of a terror attack.

Two European names were on the passenger list for the missing Malaysia Airlines flight, which disappeared in the early hours of Saturday en route from Kuala Lumpur to Beijing.

Mystery deepened Monday over the fate of a Malaysian jet carrying 239 people, as tests on oil slicks scotched suspicions it was aircraft fuel while the search for debris failed to yield any trace of the missing aircraft.

Laboratory analysis of the oil samples showed they were not from the Malaysia Airlines jet but were a type of fuel used by ships, the Maritime Enforcement Agency said in Kuala Lumpur.