The income tax department has conducted a "survey" operation at the head office of HSBC bank in Mumbai in connection with the black money probe against it and certain Indians who held accounts in its Switzerland branch.

Sources said sleuths drawn from the investigation and assessment wings of the department visited the bank's office in Fort area in Mumbai and, starting yesterday, made "inquiries" related to their probe against the global banking giant and its operations.

They said the bank has been issued notices in this regard earlier and the latest action was part of its "survey" operation where tax officials visit the business premises of an entity under probe.

Contacted for the bank's response, an HSBC India spokesperson told PTI: "We have cooperated continuously with the Indian authorities and continue to do so."

Sources said that I-T officials have seized some documents related to the bank's Indian operations during the operation which ended today even as summons were issued by it to some top executives of its Indian branch.