A passenger on a flight from Pakistan was arrested at Birmingham International Airport following a routine security search on Friday.
The man was on a Pakistan International Airlines flight from Islamabad to Toronto which had stopped off in Birmingham at 1130 BST to refuel.
It is believed an alarm may have gone off on board during the routine search, prompting a more detailed examination of the plane and the 192 passengers on board.
The man - understood to be a Pakistani citizen studying in Canada - was later released and allowed to continue his journey.
A West Midlands Police spokesman said the man was detained after officers were called to Birmingham International Airport at 1325 BST by security staff.
He would not give further details of why the man was held.
The plane was grounded after the alert while police carried out a thorough search.
Shortly before 2000 BST, police announced they had found nothing suspicious and were allowing the flight to continue.
The jet, flight PK781, took off from Birmingham International at 2144 BST, an airport spokeswoman said.