Mubasher: Fitch Ratings has upgraded Greece's long-term foreign-currency issuer default ratings to 'B-' from 'CCC', and maintained its positive outlook, according to a recent report.

The ratings agency attributed the rating upgrade to a reduced political risk and sustained GDP growth, Reuters reported on Friday.

Fitch said that it expected the general government debt to steadily improve, cushioned by benefits from the European Stability Mechanism (ESM) program.

The governments of the Euro zone agreed in June, to provide Greece with another 11th-hour credit lifeline worth $9.5 billion and sketched new detail on possible debt relief, Reuters added.

A key challenge for the banking sector in Greece is tackling non-performing exposures (NPEs), which remain stubbornly high at 45% of gross loans, the report noted.