Mehul Choksi, one of the central figures accused of involvment in an alleged fraud of nearly $2 billion (1.4 billion pounds) against Punjab National Bank, criticised India's investigating agencies in a letter alleging gross abuse of due process in the ongoing probe.

In a letter to the Central Bureau of Investigation (CBI), one of the lead agencies probing the alleged loan fraud, the jeweller said the seizure of his assets, bank accounts and the shutting down of all his offices in India has caused prejudice against him.

The March 7 dated letter, which was reviewed by Reuters, said investigating agencies were acting with a pre-determined mind and interfering with the course of justice.

In what has been dubbed the biggest fraud in India's banking history, Punjab National Bank (PNB) and police have accused two jewellery groups - one controlled by diamond tycoon Nirav Modi and the other by his uncle Choksi - of colluding with some bank employees to secure credit from overseas banks using fraudulent guarantees.

Both Choksi and Modi have denied the allegations and lawyers for the two key accused PNB employees in the case have also said they are innocent. The authorities have said Choksi and Modi left India before the complaint against them was filed and their whereabouts are unknown.

A spokesman for the CBI was not immediately reachable for comment on Choksi's claims.