NEW DELHI: The Central Bureau of Investigation (CBI) on Monday sealed the Mumbai branch of Punjab National Bank (PNB) which is the centre of a Rs 11,300 crore scam involving billionaire gem specialist Nirav Modi, officials said on Monday.

Three people together with two employees of PNB have been detained in the biggest swindling case in the country's banking history.

The CBI is also inquiring Vipul Ambani, the Chief Financial Officer of diamantaire Nirav Modi's Fire Star Diamond Company, officials said.

The CBI on Sunday started an exhaustive search operation at the Brady road branch of PNB in Mumbai. This place where the country's second largest state lender has witnessed Rs 11,300 crore scam in which  billionaire jewellers Nirav Modi and his business partner and Uncle Mehul Choksi are involed.

CBI officials said the agency is long-lasting the questioning of detained bank officials Gokulnath Shetty (retired) and Manoj Kharat, and the signatory of Nirav Modi's company along with other officials of PNB, to mark out the money trail and depth of the alleged fraud involving thousands of documents and digital records.

 As per reports of TOI, It isn't just public sector banks that have taken a hit from loans and guarantees to diamond firms run by Nirav Modi and Mehul Choksi. As many as 24 companies and 18 businessmen, who had taken franchise of their jewellery brand between 2013 and 2017, have filed criminal complaints of financial bankruptcy due to breach and fraud committed by the two.