(Reuters) - GQG Partners, which has a near 20% stake in India's Adani Group, saw its Australia-listed shares plunge 23% on Thursday after Gautam Adani, the conglomerate's chair, was indicted in the U.S. over charges of bribery and fraud.

GQG owns a combined stake of 19.37% in Adani Enterprises, Adani Power, Adani Green Energy and Adani Energy Solutions, according to LSEG data.

The investment firm's Australia-listed stock plunged as much as 23.1% to A$2.03, its lowest level since mid-March. The stock was last down about 22%, set for its worst day ever.

"Our team is reviewing the emerging details and determining what, if any, actions for our portfolios are appropriate," GQG said in a statement.

Earlier, 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.

The Adani Group did not immediately respond to a Reuters request for comment.