Indian state-run lender IDBI Bank Ltd has close to Rs. 20 billion ($328 million) loan exposure to companies affected by a Supreme Court order scrapping coal blocks but not all of it will be problematic, the lender's head said on Wednesday.

"We are assessing," M.S. Raghavan, chairman and managing director of IDBI Bank, told Reuters after the Supreme Court's verdict.

IDBI Bank shares were down 5.3% by 0924 GMT compared to a flat performance in the NSE index. The banking sector index fell about 1%.

($1 = 60.9650 rupees)