In a strongly-worded letter to his Swiss counterpart, Finance Minister P Chidambaram has also warned that an effective exchange of tax-related information was "extremely important" for economic co-operation between the two countries and Switzerland must honour its "rights and duties" agreed to in their bilateral Direct Tax Avoidance Convention (DTAC).

This is Finance Minister's third letter to Swiss Finance Minister Eveline Widmer Schlumpf within four months on this matter and he again reiterated that India would continue to take a position at the Global Forum about Switzerland lacking legal and regulatory framework for an effective exchange of information.

Mr Chidambaram also said that the interpretation made by Switzerland that it can not share information as per India's request was not in accordance with international standards.

Switzerland communicated its decision against sharing the information through a letter dated April 7 to Mr Chidambaram, pursuant to which India has now stepped up its pressure on the European nation, which has been long perceived as a major safe haven for alleged black money stashed by Indians and other foreign nationals due to its strong banking secrecy laws.

Under global pressure, Switzerland has agreed to ease its banking secrecy laws in recent years and it also signed a revised tax treaty with India in 2011 to facilitate greater flow of information about alleged black money.

However, it has refused to share information with India about the accounts mentioned in the so-called 'HSBC list' which India had received from France through a bilateral treaty.

However, it has been widely reported that France had received that list after data was stolen by a disgruntled HSBC employee in 2011 and those names eventually found their way to tax authorities across the world including India.