LONDON, Oct 20 (Reuters) - An airline pilot has been arrested on a passenger plane at Heathrow Airport on suspicion of being above the legal alcohol limit, police said on Monday.

Officers boarded a United Airlines plane at terminal one on Sunday and arrested the 44-year-old under transport safety laws.

The pilot, who has not been named, was given police bail to Jan. 16 next year, pending further inquiries. A United Airlines spokeswoman said he has been suspended from duties.

She declined to name the flight or give further details of the incident. The Sun newspaper said it happened on flight 955, a Boeing 777 bound for San Francisco with hundreds of passengers.

In a statement, the airline said: "United Airlines' alcohol policy is among the strictest in the industry and we have absolutely no tolerance for abuse or violation of this well-established policy.

"Safety is our number one priority and the pilot has been removed from service while we are co-operating with the authorities and conducting a full investigation."

(Reporting by Peter Griffiths)