Washington, July 10 (IANS): The US's United Airlines is investigating an incident in which a pilot flushed live ammunition down a toilet during an international flight from Houston to Germany, media reported on Friday.

The incident aboard the flight to Munich occurred in June, CNN reported.

"A United pilot improperly disposed off ammunition during a flight last month from Houston to Munich," the airline said in a statement on Thursday.

"We are reviewing the incident, and the pilot remains an employee."

Under federal law, a pilot is allowed to carry weapons but only in the US.

"Under the Federal Flight Deck Officer programme, eligible flight crew members are authorised by the Transportation Security Administration (TSA) to use firearms to defend against an act of criminal violence or air piracy attempting to gain control of an aircraft," the TSA said.

Eligible crew members are not allowed to bring firearms or ammunition when flying outside the US or when not on duty.