Continuing its Supreme Court-monitored probe into the 2G spectrum scam, the Central Bureau of Investigation (CBI) on Thursday questioned Essar Group CEO Prashant Ruia.
On Wednesday, Anil Ambani, the chairman of Reliance Communications, had appeared before the CBI.
The investigating agency has also quizzed other top private sector executives including Tata Realty CFO Kishore Saletore, and managing director Sanjay Ubale; Arun Mandhana, the CFO of S-Tel; and Sandip Basu, the CEO of Loop Tele.
The CBI is probing the Essar group's links with Loop Tele, which it had promoted.
The agency is acting at the behest of the Supreme Court, which has asked it to check the eligibility criteria of operators who won the 2G spectrum licenses.
The group is also a partner in Vodafone Essar, the third-largest mobile service provider in India.