MUMBAI: The Swiss unit of HSBC Plc has apologised to Mukesh Ambani for embroiling him in an investigation by India’s income-tax authorities after the Reliance chairman’s name cropped up in a list of people with beneficiary accounts in Switzerland. In a recent letter to Ambani, the bank clarified that neither he, nor Reliance Industries, was the owner of any beneficiary account with the bank’s private banking division.

The letter, signed by Petra Muheim Quick, the bank’s deputy general counsel in Switzerland, and Stephen Barney, director of the private banking business, attributes the situation to “administrative errors”, which it blames on Ambani’s past association with Flag Telecom, which had a commercial account with the bank.

Some months ago, the French authorities had handed India a detailed list of people with beneficial accounts in HSBC, Switzerland. This information has been used by the Indian authorities to levy additional taxes on people suspected of stashing money in undeclared overseas accounts.

The information became available after an HSBC employee stole the data and handed it over to the French authorities. In June 2011, the Swiss arm of the London-headquartered bank, HSBC Private Bank (Suisse) SA, was told by the Swiss government that France would share the data with India.

The letter, whose contents were described to ET by people familiar with it, acknowledges that Ambani’s name was wrongly included in that list. “During our internal review and investigation following the data theft, we have established that due to an administrative error your name has been incorrectly connected to certain accounts held with us which we would confirm to you were not connected with you either as holder or beneficial owner of these accounts,” it says.

This erroneous information we believe might be part of the data to be shared with the Indian authorities,” the letter adds.

“We can advise that the records have been corrected. Finally, after having reviewed our files, we can confirm that neither at the time of the data theft nor today you or Reliance Industries Limited have been or are the holder, or, from our records, the beneficial owner of any account with our bank in Switzerland.” The letter then appears to acknowledge the inconvenience caused.

“Clearly, we understand that this is not an acceptable situation for you. Please accept our unreserved apologies in this respect,” the letter adds. A Reliance Industries spokesperson did not reply to an email questionnaire on the issue. “We will be unable to respond to your queries on account of customer confidentiality,” an HSBC spokesperson said. The significance of the letter lies in the fact that it confirms that Ambani’s name was indeed in the list of people with overseas accounts given to India by the French authorities.

The Indian government and the Income-Tax Department have not publicly confirmed this fact before. The tax authorities are believed to have sought details of the overseas account from Ambani and sent him so-called demand notices asking for more tax.