NEW DELHI: Federal law enforcement officials have named an MP from India's ruling Congress party in an investigation into irregularities in the award of coalfield concessions, piling more pressure on the government firefighting the latest in a series of scandals.

The news emerged on the same day as officials raided the offices and homes of five companies, also in connection with the scandal that has sparked a political crisis at a time when the government is struggling to revive India's slowing economy.

The Central Bureau of Investigation (CBI) has filed a case against Vijay Darda, a lawmaker in India's upper house, a CBI official told Reuters on Tuesday. The official declined to comment on media reports that Darda was linked to companies being investigated.

Darda has denied any wrongdoing. The agency has filed cases against five companies and charged a number of officials with criminal conspiracy, cheating and intention to commit a crime, CBI officials said.

No arrests have yet been made, although documents have been seized in raids in 11 cities across the country.

“During the course of the investigation, if we will find any kind of irregular activities or illegal activities from any person, we will arrest him or her,” a CBI official said.

The five companies, which are not listed on stock exchanges, are small-time players in the main coal-producing states of eastern India. They are Vini Iron & Steel, JLD Yavatmal Energy, Jas Infrastructure and AMR Iron & Steel and Navabharat Power Ltd., the CBI officials said.

The cases have been registered in connection with allegations that the companies connived with government officials to submit false claims while applying for coalfield concessions, the CBI said.

Jas Infrastructure confirmed there had been a raid on its corporate office. An employee at the office of Vini Iron & Steel, in the eastern state of Jharkhand, said the office had been closed.

“The management didn't allow employees to enter inside. The office is shut,” the employee said by phone. There was no confirmation from other companies.