The U.S. the Securities and Exchange Commission has issued a summons to Indian billionaire Gautam Adani, indicted on U.S. bribery allegations related to a bombshell federal indictment against him, a court filing showed.

Indian billionaire Gautam Adani and his nephew, Sagar Adani, were summoned by the US Securities and Exchange Commission to explain allegations that they paid more than $250 million in bribes to win solar-power contracts,

Indian tycoon and one of Asia's richest men, Gautam Adani, may be facing his biggest challenge yet with an indictment by U.S. prosecutors for alleged fraud and bribery. But it was unclear just how far the implications will affect his businesses and own future — as well as the Indian economy and government.