Official sources said the ED has asked either Singh or his authorised signatory to be present before its officials on August 31 along with documents related to the finances in the personal and official capacity.
When contacted, Vodafone declined to comment.
The ED, according to sources, has been probing a foreign investments case against the telecom major since 2007, after it was referred by the Central Vigilance Commission (CVC).
Singh has been asked to submit documents related to his personal investments and details of remittances received by him in the last six years from overseas, the sources said.
The ED is probing if the telecom firm received funds and complied with the RBI norms with regard to the Foreign Exchange Management Act (FEMA).
