Rating agency Fitch upgraded Greece's long-term foreign and local currency issuer default ratings to "B-" with stable outlooks from "restricted default" on Tuesday.

It is the first time Greece's rating has been upgraded since the country's sovereign debt crisis broke out by the end of 2009 and the first Fitch upgrade since 2003.

Fitch withdraw the ratings on the bonds issued by the Republic and governed by Greek law and assigned "B-" ratings to Greece's new government bonds created as a result of the private sector involvement debt exchange.

Eurogroup President Jean-Claude Juncker announced late Monday that eurozone finance ministers have politically adopted the 130-billion-euro (about 171 billion U.S. dollars) second bailout program for Greece.

However, the issue ratings on foreign-law bonds will remain "C" pending settlement on April 11, while the issue ratings of securities not eligible for the bond exchange remain unchanged.

The rating agency also warned investors of significant writedowns to face value and difficulties of the country's economy, which is in its fifth year of recession.

"In Fitch's opinion, these considerations limit the potential gain that could be derived from any future restructuring of private sector bond holdings and underline the burden that could fall on official creditors," said a Fitch statement.

Fitch downgraded Greece's sovereign rating to "restricted default" last Friday, hours after the Greek authorities and eurozone officials confirmed that Greece's debt swap deal will proceed.