agency to cut France's top rating, after Standard and Poor's did so in January. Fitch has maintained its assessment of French debt so far.
In keeping France on a negative outlook, Moody's signalled that its rating could be cut again in the medium term, and the news came against a background of political tension between President Francois Hollande and allies on the left, but also amid intense political bickering among the opposition.
Moody's statement pointed to many structural problems with the French economy which made it harder to compete on a global level, noting that Paris could face fiscal issues in the future and that it was exposed to demands for financing from heavily-indebted eurozone partners.
The ratings agency took note of reform plans that have been unveiled by the new Socialist French government, but added: "The track record of successive French governments in effecting such measures over the past two decades has been poor."
French Finance minister Pierre Moscovici told AFP the downgrade was an "indictment of past management," a reference to the previous conservative government, which would incite the new government to "quickly put into effect" the already announced reforms.
France is still "well rated," Moscovici pointed out, while insisting that "this decision concerns the situation left by our predecessors."
Moody's said its decision was based on three factors, the first of which was "the risk to economic growth, and therefore to the government's finances, posed by the country's persistent structural economic challenges.
"These include the rigidities in labour and services markets, and low levels of innovation, which continue to drive France's gradual but sustained loss of competitiveness and the gradual erosion of its export-oriented industrial base."
The International Monetary Fund and the COE-Rexecode Institute, which is close to French employers' associations, have also warned that France could lose market share to countries from southern Europe that have approved robust economic reforms.
"As a result, Moody's sees a continued risk of fiscal slippage and of additional consolidation measures. Again, based on the track record of successive governments in implementing fiscal consolidation measures, Moody's will remain cautious when assessing whether the consolidation effort is sufficiently deep and sustained," the statement said.
France's fiscal perspectives were further undermined by "subdued domestic and external demand," in part owing to tax increases and weak growth in disposable income.
Finally, Moody's warned that Paris could find itself on the hook to finance bail-outs for eurozone partners via the European Stability Mechanism (ESM), and noted: "France is disproportionately exposed to peripheral European countries such as Italy through its trade linkages and its banking system."
The ratings agency said that "the predictability of France's resilience to future euro area shocks is diminishing."
Moody's stressed that France still had an excellent rating because of its "significant credit strengths," a "large and diversified economy" and "the government's commitment to structural reforms and fiscal consolidation."
But it maintained France's negative outlook owing to the eurozone economic recession and "substantial" challenges to the government's reform plans.
The downgrade put France behind eurozone partners like Finland, Germany, Luxembourg and the Netherlands, which have retained top AAA ratings though they all have a negative outlook from at least one of the three agencies.
It came less than a week after the British weekly The Economist called France "the time-bomb at the heart of Europe" for many of the same reasons as those pointed to by Moody's.
Meanwhile however, the Financial Times ran an editorial piece on Monday in which Wolfgang Muenchau noted that France "has often defied negative expectations" and "is often more resilient than forecasters and commentators generally acknowledge."