According to Bloomberg, the banker sent messages containing trade secret details to the financial services provider, Standard Chartered and his own personal email account.
The trader, who now works as the head of corporate flow sales for Deutsche Bank in Asia, has denied the allegations.
He spent 15 years working for Citigroup in various locations across Asia.
An investigation was launched by Citigroup after a senior executive at the financial service provider heard how Mr Hazarika had given Deutsche Bank âeverythingâ when he joined.
Siraj Omar, head of litigation at Premier Law, told the news provider that the case showed how increasingly competitive banks have become over the contact books of traders.
âThe idea is to make things as difficult as possible for the bankers who are leaving, which is only logical from the banksâ perspective,â he explained.
Mr Hazrika was reported by Bloomberg as saying he had done nothing wrong.
By Jim Ottewill