Securities regulator and customs authorities are investigating some Adani Group companies for non-compliance of rules, junior finance minister told parliament on Monday.
It was not immediately clear when the Securities and Exchange Board of India (SEBI), or the Directorate of Revenue Intelligence (DRI) launched the investigation.
The minister, Pankaj Chaudhary, did not name which companies were involved.
Shares of Adani group companies, which operate airports and ports, power generation and transmission, coal and gas trading, closed between 1.1%-4.8% lower on Monday.
"SEBI is investigating some Adani Group companies with regard to compliance with SEBI Regulations. Further, the Directorate of Revenue Intelligence (DRI) is investigating certain entities belonging to the Adani Group," Mr Chaudhary said.
Stocks of companies controlled by billionaire Gautam Adani last month recorded their biggest-ever declines in the week ending June 18, after newspaper Economic Times reported the accounts of three Mauritius-based foreign investors in Mr Adani companies had been frozen.
Shares in the six Adani companies have fallen between 12.9%-44.9% in the five weeks after the Economic Times report.
The stocks have cumulatively lost over $37.6 billion in just over a month after the Economic Times report, even after Mr Adani rejected the article as "blatantly erroneous."
A spokesman for the Adani group did not immediately respond to an email seeking comment.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)