LONDON: Greece's credit rating was cut by Standard & Poor's and the company threatened to take further action unless Prime Minister George Papandreou tackles the European Union's largest budget deficit.

The rating was lowered by one level to BBB+ from A-, S&P said in a statement late on Wednesday. Fitch Ratings on Dec 8 cut Greek debt to BBB+. Papandreou two days ago pledged "radical" measures to fix Greece's budget.

"The ratings could be further lowered if the government is unable to gain sufficient political support to implement a credible medium-term fiscal consolidation program," S&P credit analyst Marko Mrsnik in London said.