Indians love many things about Switzerland: chocolates, watches, Bollywood movie locales and secret bank accounts.

Until now.

India and Switzerland on Monday signed a pact amending the existing double taxation avoidance agreement, that will make it easier for New Delhi to gain access to information on suspect bank accounts, possibly paving the way to recovering billions of dollars in undeclared wealth.

It is anyone’s guess just how much money is stashed away in secure vaults in the scenic Alps.

The main opposition Bharatiya Janata Party, which made repatriating “black money” one of its election promises last year, estimates there may be some 25,000 trillion rupees, or roughly half India’s GDP of $1 trillion, in secret Swiss accounts.

Other estimates are even higher.

A report from Global Financial Integrity last year said $23-$27 billion in illicit money left India every year in the period 2002-06; some of it to offshore financial centres, and the rest to tax havens and traditional banks including big Swiss banks.