Toyota, already suffering from several massive recalls, has a new problem. The National Highway Traffic Safety Administration says it has opened an investigation into the 2010 Toyota Prius.

NHTSA said it has received over one hundred consumer complaints about the Prius losing the ability to brake when traveling on bumpy surfaces.

A Toyota spokesman said the company would "cooperate fully" with the investigation.

The Japanese government also told the automaker to investigate reports of brake failure on some Prius models. The Japanese Transportation Ministry cited 14 reports of brake failure in the latest hybrid since it went on sale in May 2009.

A leading British traffic and criminal lawyer urged the owners of almost 181,000 vehicles recalled by Toyota in the UK to park them or face being charged with dangerous driving if they were in an accident.

The Prius is Toyota's third best-selling model in the U.S., with only the mid-sized Camry and compact Carolla outselling it.