Ratings agency Standard & Poor's on Tuesday revised Greece's outlook to negative, saying the debt-ridden euro zone country could need more help from its international creditors.
"Following delays in implementing budgetary consolidation measures and a worsening Greek economy, we believe Greece is likely to require additional financing for 2012 under the EU/International Monetary Fund (IMF) program," S&P said in a statement.
"We are revising the outlook on the long-term ratings on Greece to negative, reflecting the possibility of a downgrade if Greece fails to secure the next disbursement of the EU/IMF Program," S&P said.
Greece is behind on targets agreed under a 130 billion euro financial rescue package.
The resumption of bailout funding hinges on a progress report by the EU, IMF and European Central Bank inspectors, which is not expected before September.
"We see the likelihood of shortfalls, owing to election-related delays in the implementation of budgetary consolidation measures for the current year, as well as the worsening trajectory of the Greek economy," S&P said.
The ratings agency said it sees the Greek economy shrinking by 10 percent to 11 percent, cumulatively, during 2012-2013.
S&P also affirmed Greece's CCC rating, which is already well in speculative territory.
Moody's Investors Service rates Greece C, and Fitch rates the country CCC.