Shares of Adani Group companies fell sharply on Thursday after U.S. prosecutors charged the billionaire chairman of the Indian conglomerate in an alleged bribery and fraud scheme.

Gautam Adani's flagship company Adani Enterprises fell 10% in pre-open trade, while Adani Ports, Adani Total Gas, Adani Green, Adani Power , Adani Wilmar and Adani Energy Solutions , ACC, Ambuja Cements and NDTV fell between 7% and 18%.

U.S. authorities said Adani and seven other defendants, including his nephew Sagar Adani, agreed to pay about $265 million in bribes to Indian government officials to obtain contracts expected to yield $2 billion of profit over 20 years, and develop India's largest solar power plant project.

Adani did not immediately respond to Reuters' requests for comment. ($1 = 84.4000 Indian rupees) (Reporting by Sethuraman NR; Editing by Muralikumar Anantharaman)