Undercover police posing as foreign tourists Thursday nabbed 20 taxicab drivers on charges of using hidden electronic devices to increase fares on their meters, charging riders as much as $200 for a $32 ride from the airport.

The arrests capped a nine-month investigation into the use of manually controlled "zappers" to accelerate cab meters and register fares that are vastly higher than those legally allowed, officials said."This sting operation is only one example of the types of crimes being perpetrated by unscrupulous members of the taxicab industry," said city Investigation Commissioner Kevin Frawley.

The sting used 50 city police officers, most of Asian descent, who posed as foreign travelers arriving at the British Airways Terminal at Kennedy International Airport.

"Their favorite victims are Asians traveling from the airports to downtown," city Investigation Department spokesman Ron Davis said of the dishonest drivers.

The undercover officers hailed 50 medallion cabs - those licensed to operate by the city Taxi and Limousine Commission - over a four-hour period beginning at 10 a.m. Thursday. Of the 50 drivers, 20 "zapped" passengers, Davis said.

The investigation earlier found that dishonest drivers were targeting Asians in particular.

"It's not unusual for the normal fare, say from the Tokyo airport, to be the equivalent of $200, so for them to come to the states and be told that this cab ride is $200 wouldn't faze them," Davis said.