A documentary is to reveal what it calls "serious security lapses" at Birmingham International Airport (BIA).
The airport said it had launched an inquiry and had taken action
An undercover investigation by ITV1's Tonight with Trevor McDonald found security officers sleeping while on duty and inadequate passenger searches.
A six-month project looked at the work of ICTS UK, one of the security firms used by BIA.
BIA said the allegations related solely to ICTS UK which, like the airport, said it had launched an investigation.
A statement from ITV said the investigation into the security firm also found planes left unguarded, poor staffing levels and luggage sent for extra checks ignored by officials.
The programme, to be broadcast on Monday evening, will show a US Congress security expert calling for flights from the airport to America to be grounded after watching the footage.
ICTS UK is contracted by BIA to supply security staff to a number of airlines operating out of the airport, including US operator Continental Airlines.
In a statement, BIA said it had launched an inquiry following ITV's undercover investigation and had taken action.
It said ICTS UK provides "secondary screening to a limited number of airlines at BIA".
The statement added: "From the evidence provided by ITV two weeks ago, an investigation was immediately launched involving the UK Regulatory and Security Authorities and the airlines concerned.
"We are confident that the actions already taken continue to assure the safety and security of passengers."
The statement added that the airport was concerned that some security procedures may have been misunderstood.
In a statement issued to ITV for use on its programme, the security firm said: "ICTS UK takes very seriously any allegations concerning the security we provide to our customers.
"Upon receiving the Tonight with Trevor McDonald report, ICTS UK immediately initiated a full and thorough investigation into the limited material made available to us."
A spokesman for Continental Airlines told the programme: "The company views all allegations relating to security with concern.
"Continental is committed to the highest standards of security for all its flights, and continues to work with ICTS and Birmingham International Airport to ensure these standards are maintained."
"Terror in the skies" will be broadcast on ITV1 in a Tonight special at 2100 BST on Monday.