Standard & Poor's declared Greece was in selective default on long- and short-term ratings because of the sovereign debt deal announced last week, The Financial Times reported.
"We lowered our sovereign credit ratings on Greece to (selective default) following the Greek government's retroactive insertion of collective action clauses [enforcing losses on investors who do not voluntarily sign up] in the documentation of certain series of its sovereign debt," S&P announced.
However, the ratings agency said it would "likely consider the selective default to be cured and raise the sovereign credit rating on Greece to the 'CCC' category [from CC and C]" if the debt swap is "consummated," the newspaper said.
"If a sufficient number of bondholders do not accept the exchange offer, we believe that Greece would face an imminent outright payment default."
Greek officials said the European Council and Eurogroup ministers had "anticipated, planned for and addressed" the consequences of the bailout deal, the newspaper reported.
Fitch Ratings last week downgraded Greece to C and Moody's Investors Service has said it will also cut Athens' credit rating.
S&P said it had put the European Financial Stability Facility, which will raise funding for the bailout, on negative outlook. The Daily Telegraph reported the EFSF's credit profile had been weakened because some of its guarantor nations had been downgraded from a AAA credit rating.
German Chancellor Angela Merkel Monday told the Bundestag that although some see Greece as "a hopeless case," pushing Greece to go back to the drachma could have "incalculable and therefore irresponsible" consequences, The Financial Times reported.