The international policing organisation Interpol says more than a billion travellers last year boarded planes without their passports being checked against its data base of 40 million lost or stolen passports.
Interpol has confirmed the passports used by passengers on flight 370 were entered into Interpol's database after they were stolen in Thailand where there is a thriving passport racket.
In a rare intervention as investigations are stepped up into the passengers on flight 370, Interpol secretary-general Ronald Noble said his organisation has long asked why countries ''would wait for a tragedy to put prudent security measures in place at borders and boarding gates.''
''Now we have a real case where the world is speculating whether the stolen passport holders were terrorists, while Interpol is asking why only a handful of countries worldwide are taking care to make sure the persons processing stolen passports are not boarding international flights,'' Mr Noble said of the Malaysian flight.
Malaysia's prime minister Najib Razak has ordered an urgent review of his country's air travel security procedures as investigators in Kuala Lumpur pore over CCTV footage of the passengers on flight 370 and question immigration officials and guards at the city's international airport.
''Every indicator shows some sort of security lapse, but I cannot say anything further right now,'' said a security official with knowledge of the investigation.
Investigators are trying to uncover the true identities of the passengers who used the stolen passports of Italian Luigi Maraldi, 37 and Austrian Christian Kozel whose passports were stolen on the Thai resort island of Phuket.
Malaysia's Home Minister Ahmad Zahid Hamidi said the passengers were of Asian appearance and criticised border officials for allowing them through security check-points.
''I am still perturbed. Can't these immigration officials think? Italian and Austrian (passport holders) but with Asian faces?'' he said.
The behavior of the bogus travellers is highly suspicious, fueling speculation that a terrorist attack brought down the plane.
But Malaysian officials stress they have no evidence indicating what caused the plane to disappear during a red-eye flight from Kuala Lumpur to Beijing in the dark early hours of Saturday morning.
Flight booking information shows the passengers bought the tickets together at a travel agency in Pattaya, a seaside city outside Bangkok that is a known haunt of international criminal networks.
They booked the flight to Beijing where they would not have had to clear customs before taking another flight from Beijing to Amsterdam.
One, travelling under Maraldi's name, was due to proceed to Copenhagen and the other to Frankfurt, Germany.
The real Mr Maraldi was brought to a police press conference in Phuket where he is holidaying, telling how he reported his passport stolen on August 1 last year while on a previous holiday in Thailand.The men paid for the fares in Thai baht.
The passport went missing after he deposited it to rent a vehicle at a business in Patong, the red light tourist area on Phuket where hundreds of passports are lost or stolen every year.
Mr Noble said some of Interpol's 190 member countries cite a lack of police resources, privacy concerns or political hostilities with other countries for their failure to check passports against the global date base.
Four of every 10 international passengers are not screened against the database, he said.
The database draws on information from 167 countries.
In Thailand passport forgery and theft is a huge underground business. Last year police caught a Thai man with 5000 fake passports.
Forgers are using advanced technology to make fake passports.
Thai police general Warawuth Thaweechaikam said: ''it must take great skills and expertise by our officers to detect the fake passports and visa stamps because the system cannot detect them the whole,'' he said.
Mr Najib, the prime minister, said security at Malaysia's airports would be improved after the review but stressed the cause of the plane's disappearance remains inconclusive.
''We need to look at all the possible leads before reaching a conclusion . . . we still do not know what really happened and have yet to obtain any substantial leads,'' he said.
Qantas said it could not detail whether its passengers were checked against Interpol's Stolen and Lost Travel Documents database, citing security and confidentiality restrictions.
''Qantas works closely with law enforcement agencies in Australia and overseas, but for security reasons we cannot disclose the detail of those arrangements,'' a spokesman said.
The US searches the Interpol database annually more than 250 million times; the UK more than 120 million times; and the United Arab Emirates more than 50 million times.