NEW YORK (CNNMoney.com) -- In the wake of massive recalls for gas pedal-related problems, Toyota Motor Co. is now faced with mounting complaints of brake problems in its 2010 Prius hybrid, one of the carmaker's most iconic and popular models.
In the U.S., more than 100 complaints alleging poor brake performance have been lodged with the National Highway Traffic Safety Administration against the 2010 Prius, a newly designed version of the car that was introduced last summer.
"NHTSA has received a number of complaints about a potential defect affecting the brake system in Toyota's Prius hybrid and is conducting field work to examine the issue," the agency said Wednesday.
In Japan, 14 complaints about brakes in the Prius have been lodged since July. Japan's Transportation Ministry has asked Toyota to investigate brake malfunction complaints in Japan on the Prius, according to the Japan Automobile Dealers Association.
"The complaints received via our dealers center around when drivers are on a bumpy road or frozen surface," Paul Nolasco, a Toyota Motor Corp. spokesman in Japan, said. "The driver steps on the brake and they do not get as full of a braking feel as expected."
A search of NHTSA's complaint database turned up many similar-sounding complaints in the U.S.
"I have been driving my 2010 Prius for 6 months and have experienced the following nearly 10 times," wrote one owner, "When braking, if a pothole or bump in the road is hit, the car seemingly jerks forward/accelerates for a split second."
A Toyota spokesman in the U.S. was not immediately able to provide any comment on the situation.
The Prius is Toyota's third best-selling model in the U.S., ranking behind only the Camry midsized sedan and the Corolla compact car.
Toyota's public image, and its sales, have been hit by recent recalls involving unintended acceleration.
Toyota recalled 2.3 million vehicles on Jan. 21 due to problems with sticking gas pedals and later halted the sale of the eight models involved in the recall.
Toyota's U.S. sales plunged 16% in January as a result, even as sales of other automakers rose.
About 4.2 million vehicles were recalled in November for a problem in which the cars' gas pedals could get stuck in some floor mats. The last-generation version of the Prius was included in that recall, which was expanded to include another 1.1 million last week.
Brakes in hybrid cars like the Prius operate differently from brakes in most cars. In addition to standard brakes, which use friction from pads pressed against drums or rotors, hybrid cars use their electric motors to help slow the car, a process that generates electricity to recharge the batteries.