About 48 lakh (4.8 million) demat accounts have been frozen by the two depositories, National Securities Depository Ltd (NSDL) and Central Depository Services Ltd (CDSL), because investors failed to submit Income Tax Department's Permanent Account Numbers.

NSDL, in a press release here, said of its 77 lakh (7.7 million) demat accounts, 42 lakh (4.2 million) accounts have been frozen. Of this, 16.6 lakh (1.66 million) accounts have share holdings while 18.6 accounts had nil positions.

"Of a total of 22 lakh (2.2 million) accounts, 5.92 lakh (592,000) accounts were frozen, effective from January 1. Of this, 2.5 lakh (250,000) accounts have holdings while 3.35 lakh (335,000) accounts have nil position," a spokesman for CDSL said.

Meanwhile, in a separate release, CDSL said it had been conferred with Information Security Management System Standard (ISMSS) from Det Norske Veritas (Rotterdam), signifying that its operations were in conformance with the ISMSS.

The certification covers depository services provided through depository participants (DPs), provision of services to issuers and registrars for processing of corporate actions, and the provision of Internet-based access to their accounts to DPs and investors. CDSL has obtained the certification for not only its main site, but also for its disaster recovery site (DRS).