THE US Federal Bureau of Investigation (FBI) is using a fleet of civilian aircraft registered with phoney front companies to snoop on citizens, it emerged on Monday.

The powerful and shady agency was forced to admit to the domestic spying programme following a journalistic investigation by the Associated Press.

The light aircraft seen flying over US cities carry video and mobile-phone surveillance equipment and are generally employed without a judicial warrant.

They have been traced to at least 13 fake companies such as FVX Research, KQM Aviation, NBR Aviation and PXW Services.

The FBI claims the flights are used for specific ongoing investigations. In a recent 30-day period the agency flew over more than 30 cities in 11 states across the country.

“The FBI’s aviation programme is not secret,” FBI spokesman Christopher Allen claimed, but added: “Specific aircraft and their capabilities are protected for operational security purposes.”

Mr Allen stresses that the FBI’s planes “are not equipped, designed or used for bulk collection activities or mass surveillance.”