Basu, who arrived here in the morning, was questioned on shareholding patterns and its alleged financial dealings with Essar group.
CBI is investigating whether Loop acted as a front for Essar group in getting telecom licences in alleged violation of rules, an allegation refuted by Essar group.
The agency has sent Letters Rogatory to Mauritius seeking details of ownership patterns of Loop Telecom which had got telecom licences in 22 circles, despite being ineligible for the same as pointed out by Comptroller and Auditor General in its report.
The CAG in its report has said that the Loop Telecom was not eligible for grant of Unified Access Service licence on the day they submitted their application which is September 3, 2007.
"The company had changed the main object clauses in their MOA/AOA so as to include the telecom sector in their MOA/AOA but these alterations were registered by the ROC on 28 September 2007 only. Thus they were also not eligible for grant of UAS licence on the date of submission of their application in September 2007," it said.