Ratings agency Moody's has downgraded Greece's sovereign debt ratings by three notches to Ca with a developing outlook from Caa1 and said the country still faced serious medium term solvency challenges.

Last week, euro zone leaders agreed on a bailout package that will make it easier for Greece to reduce debt by easing terms of loans and by making investors in Greek bonds shoulder some of the burden.

(Reported by Cecile Lefort)