Fitch followed on Friday with a cut by two notches to AA- from AA+.
Earlier this month Moody's slashed Italy's credit rating, following a similar move by S&P in September.
Meanwhile, Fitch cut the debt ratings on government-guaranteed bonds issued by ANZ-National Bank and Westpac yesterday to reflect its downgrade of New Zealand's sovereign rating last month.
The debt was lowered to AA from AA+, the agency said.
The downgrades cover US$2.4 billion ($3.01 billion) of 2012 and 2014 bonds issued by ANZ-National and US$2.5 billion of Westpac bonds of similar maturities.
- Staff reporter, AP, APNZ