New Delhi, Feb 13: Indians are the largest depositors in Swiss banks and have stashed away $500 billion in black money in overseas tax havens, but the government is finding it "difficult" to recover the ill-gotten wealth as other nations are not cooperating, officials said Monday.

Disclosing the estimated amount of Indian black money in foreign banks, Central Bureau of Investigation (CBI) Director A.P. Singh said India suffered from the flow of illegal funds to tax havens like Mauritius, Switzerland, Lichtenstein and British Virgin Islands.

"It is estimated that around $500 billion of illegal money belonging to Indians is deposited in tax havens abroad," he said at the opening of a six-day training programme for Interpol officers.

Minister of State for Personnel V. Narayanasamy, who inaugurated the CBI training programme, said the recovery of black money needed cooperation from other nations.

"Political will in other countries is not very encouraging. They say we are bound by laws," the minister said.

"We are finding it difficult to bring back black money stashed away in foreign banks."

The Indian government has drawn bitter criticism from opposition parties and activists and faced heat in the Supreme Court for its alleged failure to get back the ill-gotten wealth.

A study by the Global Financial Integrity last year estimated that $462 billion of Indian black money was parked in overseas tax havens.

The CBI chief agreed with the minister's view and said "inadequate international cooperation and bank secrecy laws" had made it difficult to trace and get back the stashed away "stolen wealth".

"Tracing, freezing, confiscation and then repatriation of stolen assets is a legal challenge," A.P. Singh said.

He said obstacles included "legal process filled with delays and uncertainty, language barriers and a lack of trust when working with other countries".

The CBI chief expressed surprise that offshore tax havens were those countries which were "said to be least corrupt as per the Transparency International index".

"Fiftythree percent of the countries said to be least corrupt are offshore tax havens, where most of the corrupt money goes. The tax havens include New Zealand, which is ranked the least corrupt country, Singapore is ranked number 5 and Switzerland number 7."

The minister warned that tackling black money had assumed significance because terror outfits were repeatedly using innovative electronic ways to deposit wealth in tax havens "for siphoning off funds for terrorism related activities".

The CBI director cited World Bank estimates and said the cross-border flow of money from criminal activities and tax evasion was around $1.5 trillion, of which $40 billion is bribe paid to government servants in developing countries.

He said only $5 billion of this money had been repatriated in the last 15 years.

The six-day training exercise, a first by the CBI, is being attended by 30 Interpol officers from countries like Afghanistan, Sri Lanka, Britain, China, Malaysia, the Philippines and Indonesia. This is part of Interpol's initiative on anti-corruption and asset recovery.