The Directorate of Revenue Intelligence has accused Adani Enterprises Limited of trying to obstruct its investigation into the overvaluation of coal imports by some group firms, The Indian Express reported on Friday.

In an affidavit to the Bombay High Court on June 13, the agency said Adani Enterprises was doing this by challenging the “well-settled procedure of issuance of Letter Rogatory”. Letters rogatory are formal requests to foreign countries to seek judicial help in investigating offshore entities.

In August, an Adani Group company moved the Bombay High Court seeking to quash all requests by India to other countries for help in investigation. It did so after a Singapore court directed some group companies to produce documents in an investigation after receiving a letter rogatory from India. The next month, the Bombay High Court gave an interim stay to Adani Enterprises but the Directorate of Revenue Intelligence moved the Supreme Court as its investigation was forced to stop. The top court has now directed the Bombay High Court to settle the case by the end of June.

The Directorate of Revenue Intelligence is investigating at least 40 companies, including those from the Adani Group, Anil Dhirubhai Ambani Group, and Essar Group for alleged overvaluation of coal imports from Indonesia between 2011 and 2015. In March 2016, the Directorate of Revenue Intelligence had alleged that Indonesian coal was imported directly to India but import invoices were routed through intermediaries – allegedly subsidiaries of Indian companies – in other countries to artificially inflate the value.

The investigating agency in its affidavit pointed out that Adani Enterprises sought to quash the Letters Rogatory only after the Singapore court allowed India’s request. The documents from the Singapore group company had “clinching evidence” against Adani Group’s “blatant” increase in prices of imported coal so that it could siphon money and increase the cost of power in India.

In its petition to the Bombay High Court last year, Adani Enterprises had claimed that the Letters Rogatory were issued without any notice or registering of an FIR. But the DRI, in its June 13 affidavit, said that investigations under the Customs Act, Prevention of Money Laundering Act, Wildlife (Protection) Act and the Companies Act “does not commence by registering FIRs or by seeking an order from a Magistrate unlike the police officers”. The coal investigation, under the Customs Act, thus did not require an FIR.

“AEL [Adani Enterprises] has frivolously invoked unrelated and inapplicable principles such as fundamental rights to cast aspersions on a diligently followed investigation procedure adopted by the DRI,” said the affidavit.