Shares of Reliance Infrastructure and Reliance Natural Resources Ltd [Get Quote] on Tuesday tanked in the range of 4-8 per cent on the bourses after reports surfaced that these two ADA Group firms are involved in fraudulent banking activities overseas.

Shares of Reliance Infrastructure, erstwhile Reliance Energy Ltd [Get Quote], plunged 7.63 per cent to a low of Rs 603.20. It was later quoting at Rs 626, down 4.14 per cent on the BSE.

Similarly, Reliance Natural Resources Ltd (RNRL) dropped 4.26 per cent to a low of Rs 56.25 on the Bombay Stock Exchange. It was later trading at Rs 56.80, down 3.32 per cent in the afternoon trade.

Media reports on Tuesday said the two ADA Group firms -- RNRL and REL -- were involved in fraudulent activities in the London branch of Swiss banking major UBS.

"Overdrafts had been fraudulently drawn against these overseas accounts in order to route funds through a number of Indian diamond traders.

"The money was suspected to have been used to buy participatory notes (PNs), derivative instruments with Indian stocks, as underlying," the report said.

It further added that the Enforcement Directorate under the Ministry of Finance was probing the matter because the transactions might amount to violation of Indian foreign exchange and anti-money laundering laws.