Boats and aircraft searching for traces of a Malaysian jet that vanished with 239 people on board homed in Monday on a remote Vietnamese island after possible debris was spotted floating nearby.
Two objects were seen from the air late Sunday some 50 miles (80 kilometres) off Tho Chu island, in what Vietnamese authorities said could be a breakthrough sighting of debris from the disappeared jet.
"All night we mobilised our most modern equipment for the search... but we found no sign of the objects," Vice Admiral Ngo Van Phat told AFP.
"Two boats left this morning to patrol all maritime zones around Tho Chu Island where we discovered the two objects."
Three aircraft will run sorties over the area to scour for the possible wreckage, while a command centre for search operations has been established at the larger Phuc Quoc island closer to the Vietnamese mainland.
Two large oil slicks -- suspected to be caused by aircraft fuel -- were seen on Saturday off Tho Chu.
Malaysian authorities, who have launched a terror probe after at least two of the passengers on board were found to have travelled on stolen passports, said they were continuing to comb waters closer to their shores, further south of Tho Chu. "We are concentrating on our area," said Amdan Kurish, head of the Malaysian Maritime Enforcement Agency.
The Boeing 777 departed early Saturday bound for Beijing but the flight dropped off the radar soon after take off.
It has baffled international authorities who have launched a massive hunt for the aircraft and left anguished relatives with no answers as to their loved ones' fate.
As they scramble to discover what happened, Malaysian officials have speculated that the MH370 may have inexplicably turned back towards Kuala Lumpur.
The plane, captained by a veteran MAS pilot, had relayed no indications of distress, and weather at the time was said to be stable.
Questions have also swirled over how at least two passengers boarded the jet on stolen passports, sparking a investigation into possible links with terrorism and a probe into the sale of passports in Thailand -- where the documents were stolen over the last two years.
Two European names -- Christian Kozel, an Austrian, and Luigi Maraldi of Italy -- were listed on the passenger list. But neither man boarded the plane, officials said.
The tickets booked in Maraldi and Kozel's names were made on March 6, 2014, costing around $625 and were issued in the Thai city of Pattaya, a beach resort south of Bangkok.
Malaysia's interior minister said the two passengers in question had "Asian facial features", according to a report on Monday. "I am still puzzled how come (immigration officers) cannot think: an Italian and Austrian but with Asian facial features," Home Minister Zahid Hamidi was quoted as saying late Sunday by Malaysia's national news agency Bernama.
Interpol confirmed that "at least two passports" recorded in its Stolen and Lost Travel Documents database were used by passengers on the Malaysian flight.
Malaysia's transport minister Hishammuddin Hussein said he was looking at four suspect passengers in all.
The United States has sent an FBI team to help investigate the passengers, but US officials stressed there was as yet no evidence of terrorism.
MAS shares lower
Malaysia Airlines shares lost 10% in early trading Monday as the market reacted to the jet's disappearance.
The incident is a massive blow for the carrier which has haemorrhaged cash for several years amid mounting competition from low-cost rivals such as AirAsia.
As the search entered a third full day anguished relatives of the 227 passengers and 12 crew onboard remained in the dark, after the airline admitted it feared the worst.
At a hotel in Malaysia's administrative capital, Putrajaya, several families of those onboard shared breakfast, glued to the morning news on television as little new information on the missing plane emerged.
Chinese state media on Monday lashed out at Malaysia and MAS over their handling of the crisis, with more than 150 Chinese among the missing passengers. "The Malaysian side cannot shirk its responsibilities," the Global Times newspaper, which is close to the ruling Communist Party, wrote in a scathing editorial. "The initial response from Malaysia was not swift enough."
Xinhua news agency said the Chinese government would send a working group Monday to Malaysia tasked with investigating the incident and helping family members already there.
A total of 40 ships and 34 aircraft from an array of Southeast Asian countries, China and the US have been involved in the search, with two Australian surveillance aircraft due to join.