"It is impossible for me to travel back to India. I wish to point out that the Regional Passport Office Mumbai has not given me any explanation as to why my passport has been suspended and as to how I am a security threat to India," Choksi said in a letter on Wednesday.
The 57-year-old heads Gitanjali Gems, which operates stores under banners including Gili, Nakshatra and Asmi. He said in his letter that while the CBI has seized his assets, it has yet to submit a "Seizure Memo" in court, as required by law.
Choksi, along with Nirav Modi, the jeweller to stars in India and abroad, are accused of swindling PNB by colluding with a few of its employees in Mumbai to secure credit from overseas banks using fake guarantees.
Both left India in the first week of January, long before the CBI started investigating the PNB fraud.
Choksi said in the letter he had travelled abroad on business and had gone through a cardiac procedure last month, because of which he was unable to travel for at least four to six months.
Earlier, Nirav Modi had written to the CBI that he would not be able to return to India and join investigations as he "has a business to take care of outside India".
Known as "Pappu" among diamond traders, Choksi started as a trader in Mumbai, went on to own 22 companies and became a regular in Bollywood circuit.
As the investigation into the fraud reached his multi-crore companies, he accused the agencies of "acting with a pre-determined mind and interfering with the course of justice".
Choksi also wrote about his concern for the safety of his family, and "threat by individuals with whom I have a business relationship".
He also took the 22-point letter as an opportunity to criticise the politicians for "politicising the issue with a view to glorify their own interests"; media for denying him the "right to life and fair trial"; and accused the investigators of "gross abuse of process of law". He also objected to being called a "fugitive".