The CBI received the bank's complaint late last night, official sources said, adding that the allegations are being looked into and the course of action will be decided soon.
It's unclear whether the complaint is linked to the bank's revelation this morning that it had detected a $1.8 billion (over Rs 11,000 crore) fraud at a single branch in Mumbai.
India's second-biggest state-run bank said in a regulatory filing to the stock exchange that it had detected "fraudulent and unauthorised transactions in one of its branches in Mumbai for the benefit of a few select account holders with their apparent connivance". Based on these transactions, said PNB, "other banks appear to have advanced money to these customers abroad".
Nirav Modi, 48, is being investigated by the CBI, which has filed a case against him in connection with fraud worth Rs 280 crore.
On January 29, the Deputy General Manager of a Punjab National Bank branch in Mumbai, Avineesh Nepalia, complained to the CBI that some officials were causing a loss to the bank. The bank claimed that two of its officials had issued Letters of Understanding (LoU) without following procedure and without making entries in the systems. Eight fraud LoUs amounting to Rs 280 crore were issued for Hong Kong-based banks.
Nirav Modi was also raided by income tax officials on January 31; his offices in Delhi, Surat and Jaipur were searched.
Nirav Modi is the founder of $2.3 billion Firestar Diamond and counts among his clients several world renowned celebrities. He has boutiques across three continents - in London, New York, Las Vegas, Hawai, Singapore, Beijing and Macau. In India, Mr Modi has his stores in Mumbai and Delhi.
Mr Modi was named among Forbes' list of India's Richest in 2016, with a net worth of $ 1.74 billion.
With inputs from PTI