Ratings agency S&P Global on Monday cut its long-term issue rating on state-owned SriLankan Airlines' foreign currency-denominated bond, after the airlines was unable to meet an interest payment and defaulted on a paper.

"We lowered the issue ratings on the SLA 2024 bond to 'D' from 'CC' because both the issuer and government of Sri Lanka, as guarantor, missed a coupon payment of about US$6.1 million," the ratings agency said in a statement on Monday.

SriLankan Airlines defaulted on a $175 million bond as it was unable to meet a $6 million interest payment, its chairperson told Reuters on Thursday.

S&P affirmed the other ratings on Sri Lanka and said that the outlook on country's long-term local currency rating is negative. (Reporting by Akriti Sharma in Bengaluru)