Union Minister Arun Jaitley today warned that Indians having illegal deposits in Swiss banks would face harsh penal proceedings under the black money law after Switzerland starts real-time sharing of details of accounts from January onwards.

Latest data from the Swiss National Bank showed that money parked by Indians in Swiss banks rose over 50 per cent to CHF 1.01 billion (Rs 7,000 crore) in 2017, reversing a three-year downward trend amid India's clampdown on suspected black money stashed by its citizens overseas.

"A news item has appeared today indicating an increase of money by 'Indians' in the Swiss banking system. This has led to a misinformed reaction in certain circles raising a query whether the government's anti-black money steps have yielded results," Jaitley said in a blog.

Noting that Switzerland in financial disclosures was always a reluctant state, Jaitley said the Alpine nation has amended its domestic laws involving all disclosures and entered into a treaty even with India and real-time flow of information with regard to Indians would be made.

"The flow of information is starting in January 2019. Any illegal depositor knows that it is a matter of months before his name becomes public and he will be subjected to the harsh penal provisions of the black money law in India," said the senior BJP leader and an eminent lawyer.

Further, Jaitley said those who participate in a public discourse must understand these basic facts before expressing an opinion which may be ill-informed.

"To assume that all the deposits are per se tax evaded money or that Switzerland in the matter of illegal deposits is what it was decades ago is to start on a shaky presumption," he added.

According to Jaitley, past investigations by the tax department have shown that this includes funds held by persons of Indian origin who now hold foreign passport and monies belonging to Non-Resident Indians. There were also monies belonging to resident Indians who have made legitimate investments abroad, including the transfer of money under the liberalised remittance scheme.

"It is only monies kept by resident Indian outside these categories which become actionable," he said.

Jaitley, who was Finance Minister, is currently a Minister without any portfolio as he is recuperating after a kidney transplant operation.

Prime Minister Narendra Modi-led NDA government has a multi-pronged strategy to increase the tax base, Jaitley said, adding that a campaign involving various steps to flush out black-money was initiated.

"The first big news for this year is that the advance tax deposit during the first quarter of this year has seen a gross increase of 44 per cent in the personal income tax category and 17 per cent in the corporate tax category," Jaitley said.

Because of steps taken by the government, the total income tax collection for the year 2017-18 is Rs 10.02 lakh crore, a four-year increase of 57 per cent, he said.