The Japanese banks will be able to issue letters of credit for relevant deals after the clearance from the Japanese and US regulatory authorities, one of the sources who spoke on condition of anonymity said.
These banks are expected to accept payment by Japanese refiners for importing Iranian barrels mainly in yen, the source added.
One of the Japanese banks declined to comment Tuesday.
Japanese refiners and shipping companies have recently clarified their concerns over relevant shipping insurance.
Japan's JXTG Holdings intends to resume loading oil from Iran at the end of January, while Cosmo Oil aims to load around 1.8 million barrels of Iranian crude at the end of this month upon final clearances, the presidents of the companies told S&P Global Platts on January 7.
Japan was among eight countries to receive a 180-day waiver from the US sanctions. The waiver expires in early May, when the country will be expected to cut purchases significantly.