The CBI had earlier questioned ICICI Bank executive director NS Kanan as part of its probe.
According to the Central Bureau of Investigation (CBI), the government-run PNB official Gokulnath Shetty would return these documents to top company officials after issuing the letters that enabled Nirav Modi and his uncle Mehul Choksi's companies to get credit overseas.
Earlier, a senior official of the ICICI Bank was summoned to the CBI office in Mumbai.
"The SFIO will now likely send a more detailed questionnaire to banks asking for more information and since there are 31banks involved, it is likely that the process of collecting information itself will take a few months", said a person aware of the investigation.
ICICI Bank Ltd has an exposure of Rs750 crore to the Gitanjali group of companies and Rs500 crore to Gitanjali Gems. "They have been summoned for giving the loan facility to Gitanjali Group".
"To provide assistance to the investigating authorities, representatives of ICICI Bank continue to engage actively and provide requisite inputs as routinely done in the case of all investigating authorities who approach the Bank", ICICI Bank said in a statement to the exchanges.
And, there is a LoU is guarantee that is given issuing a bank to the Indian banks with branches in the foreign to grant short-term credit to the applicant.
Chitalia was brought to the Central Bureau of Investigation office at the Bandra-Kurla Complex for interrogation.
The Enforcement Directorate (ED) is hoping to recover Rs 3,000-4,000 crore from the real estate assets seized from Nirav Modi and Mehul Choksi, sources told Moneycontrol.
Soon after the exposure of the PNB scam, Axis Bank had stated that while it had in the past done transactions against PNBs authenticated letters of undertakings, the private sector lender had since sold down all the referred transactions.
It is alleged that Choksi and Modi got Letters of Undertakings (LoUs) and Foreign Letters of Credit (FLCs) of Rs 12,636 crore issued in favour of foreign branches of Indian banks based on fraudulent claims. These amounts are then credited to the LoU issuing bank's Nostro accounts.