Entering an airport terminal without a valid ticket is illegal under Indian aviation rules.(File photo)

A US national was arrested on Thursday by the Central Industrial Security Force personnel at the Delhi airport for allegedly using a fake ticket to enter the terminal area, a senior official said.

Nishant Nagar was arrested around 1 am by the CISF while he was leaving the Terminal-3 (T3) building of the Indira Gandhi International (IGI) Airport, he said.

The man was stopped and questioned as exiting the terminal area is not allowed under normal circumstances, the official said.

The passenger told the CISF personnel that he used a "cancelled" air ticket of Mumbai to enter the terminal area to see off his friend who was travelling to Shanghai in China, he said.

The passenger has been handed over to police, which has charged him on charges of criminal trespass.

Entering an airport terminal without a valid ticket is illegal under Indian aviation rules.