Seattle, April 17 (Reuters): A contract baggage handler who became trapped in the belly of an Alaska Airlines jet on takeoff from Seattle after falling asleep in the plane's cargo hold has been banned from all future work at the airline, a company spokesperson has said.

The employee of Menzies Aviation, an airport ground services company, made news on Monday as an unintended stowaway on Alaska Flight 448 when he woke up from a nap inside the sealed baggage compartment to realise the plane was already airborne.

The pilot of the Los Angeles-bound flight, with 170 people aboard, turned the jet around to make a safe but unscheduled emergency landing back at Seattle-Tacoma International Airport after the crew heard banging beneath the aircraft.

Emerging unhurt from the plane, the baggage handler told authorities he had dozed off inside the forward cargo hold before takeoff.

He later passed a drug test and was released from a hospital where he was taken for evaluation, the airline said.

The worker, who has not been publicly identified, was never in danger because the cargo compartment was pressurised and temperature-controlled, airline officials said.

But in a panicky 911-emergency call placed after awaking inside the belly of the plane, the worker pleaded with the operator for help, screaming, "I can't breathe", before the connection was lost, according to a recording released by airport authorities on Thursday.

Also on Thursday, a spokesperson for Menzies Aviation, a subsidiary of British-based John Menzies, said the worker had been placed on administrative duties pending an investigation.

However, Alaska Airlines spokesperson Bobbie Egan told Reuters: "The employee has been permanently banned from ever working again on an Alaska Airlines operation."

She said workers were not permitted to sleep on the job.