Passengers on an airplane which came from Mexico and arrived at the John F. Kennedy International Airport in New York last week, were able to bypass customs check, a necessary requirement to avoid entrance of terrorists in the country.

The New York Post said this is already the second time in two months that such an incident has happened, at the terminal of the American Airlines.

The US Customs and Border Protection pinned the blame on the airline, saying that it was not able to have the passports of its passengers checked when they arrived at JFK airport.

"Due to an airline error, some of the international passengers were inadvertently directed to exit through a domestic gate before being processed by CBP," said spokesperson Anthony Bucci in a statement quoted by the New York Post.

He added that their office is already investigating the incident and exploring means to ensure that this will not happen again in the future.

Providing more details on what happened, New York Daily News said the American Airlines Flight 1223 arrived from Cancun, Mexico, Monday last week.

It noted that aside from the passports, the bags of the passengers were also not checked prior to entering the country.

One of the passengers shared with the New York Daily News that he found the lack of security checks absurd, since anyone can just enter the country as they please.

He explained that when he asked a Transportation Security Administration agent about the security procedure, he was told that he was fine and that he could go ahead.

The same report claimed that the lapse in security also happened with the same airlines last November.

It was added by New York Post that the American Airlines claimed responsibility for their shortcoming in security protocol.

"We take the safety and security of our customers, employees and operation very seriously. Some passengers on Flight 1223 did not complete immigration and customs process upon arrival when they were inadvertently directed to the domestic terminal," the airlines' statement furthered.

New York Daily News noted that an airline asked their passengers to return to JFK and complete the customs check. The message, however, was too late for them to properly check what the passengers carried with them from Mexico.

One of the passengers, as per the same report, tagged this measure as a desperate move from the airlines, which he claimed clearly messed up with the lack of security checks.