FBI Flying Surveillance Planes Over US Cities

The FBI is operating a fleet of low-flying surveillance planes which film people on the ground and can even identify them from the mobile phones in their pockets.

An Associated Press investigation found the agency flew at least 50 aircraft over 11 states in a recent 30-day period.

The FBI said the flights, which take off without a judge's approval, are used for specific investigations.

The news agency began investigating the flight data after the Washington Post linked two planes circling over riot-hit Baltimore in early May to the FBI.

The FBI can use the planes to identify thousands of people below by their mobile phones, using technology which imitates how cell towers find subscriber data.

AP said the practice was used by the FBI in recent weeks above Ronald Reagan Washington National Airport and the Mall of America in Bloomington, Minnesota.

The aircraft flew over more than 30 cities, including Houston, Phoenix, Seattle, Chicago, Boston, Minneapolis and Washington DC.

There are least 115 planes, including 90 Cessnas, in the FBI's surveillance fleet, according to a 2010 federal budget document.

AP traced the use of the aircraft to at least 13 front companies, including FVX Research, KQM Aviation, NBR Aviation and PXW Services, registered to post office boxes in Virginia.

A mysterious name, Robert Lindley, appears on the aircraft registrations in several signature patterns, according to AP.

A signature for one Robert Taylor, in handwriting said to be strikingly similar to one of Lindley's handwriting styles, also appears on documents.

The FBI would not disclose to AP whether Lindley is a US government employee.

It is not clear when the programme began, but the suspicious-looking planes have been circling over neighbourhoods since at least 2003.

In 2009, the FBI requested $5.1m from Congress for the air surveillance, saying it provided "indispensable intelligence collection".

FBI spokesman Christopher Allen said in a statement emailed to Sky News that the programme was not secret.

"Specific aircraft and their capabilities are protected for operational security purposes," he added.

He said the aircraft were not used for "bulk collection activities or mass surveillance".

The programme was in accordance with the FBI's own guidelines and the Attorney General's, he added.