LONDON, June 15 (Reuters) - International bonds of frontier emerging market economies surged on Monday, with many hitting levels not seen since before the U.S.-Iran war, after officials from both countries announced an agreement to end the conflict.

Data from Tradeweb showed that long-term bonds issued by countries heavily reliant on energy imports saw the biggest gains, with Sri Lankan bonds maturing in 2038 jumping more than two cents to just over 99 cents on the dollar, while Egyptian international bonds rose 1.8 cents. Kenyan and Pakistani bonds also climbed by more than one cent.

The gains also included bonds issued by Middle Eastern governments, with Saudi bonds due in 2047 rising by about one cent, while Bahraini bonds increased by 0.7 cents.

Standard & Poor's Global Market Intelligence data showed a widespread decline in the cost of insuring sovereign debt via five-year credit default swaps.