In the wake of the billion-dollar Punjab Bank (PNB) fraud, former Finance Minister P Chidambaram alleged that the accused were assisted "at some level."

The senior Congress Party leader, while speaking at the launch of his book titled Speaking Truth to Power, further cried foul and said scams were only taking place in the jewelry sector, with key players mainly from Gujarat.

"It's all happening in one sector-jewelry. Key players seem to have come from one state-Gujarat. It's not happening across other sectors and states. Obviously, people have been helped at some level. Who helped and how, I have no evidence," he said.

PNB in February had detected a 1.77 billion dollar fraud wherein noted jewelry designer Nirav Modi had acquired multiple letters of undertaking to avail credit from a number of banks.

In this regard, the state-owned lender had filed cases against Nirav Modi and his uncle, Mehul Choksi, the owner of Gitanjali Gems Pvt Ltd.

On Thursday, the Central Bureau of Investigation (CBI) registered a fresh case against two firms of Nirav Modi.

The billionaire businessman, who owns Firestarter Diamond International Private Limited, and Choksi have been accused of defrauding PNB of Rs 127 billion, including Rs 13 billion being added to the fraud kitty on February 26.