The rating on IIFCL reflects the company's position as the key agency of the government of India for facilitating the long-term financing of the country's infrastructure projects, S&P said in a statement.
The outlook remains stable, it said.
The rating also reflects our opinion that there is an almost certain likelihood that the Indian government will provide timely extraordinary support to IIFCL, sufficient to meet its debt obligations, in case of financial distress, it said.
"We have therefore equalised the rating on IIFCL with the sovereign rating," it added.