LONDON, Sept 5 (Reuters) - The world's top rating agencies are taking a cautious stance on Mario Draghi's call for tax cuts and growth-friendly tinkering of fiscal policy in the euro zone and warn France's rating would be most at risk if it fails to noticeably improve growth.
In a landmark speech last month, the head of the European Central Bank said it would be "helpful for the overall stance of policy" if fiscal policy could play a greater role alongside the ECB's monetary policy, adding: "and I believe there is scope for this".
On Thursday he expanded on the comments, stressing that while reform remained vital and the bloc's debt rules were inviolable, carefully selected tax cuts and government spending in receptive parts of the economy would be beneficial and could even be done in a "budget-neutral way".
It marks an end to the tacit coalition of ECB support in combination with German-style fiscal austerity that has been in place since the outbreak of the euro zone crisis, and leaves Draghi positioned closer to France and Italy now than Berlin.
But for rating agencies, who have only recently started to stabilise their euro zone ratings, the change of tack revives uncertainty about debt levels in countries they had hoped had pretty much peaked.
"With general government debt now close to 100 percent of GDP for the euro area overall, those sovereigns with the biggest need for growth-promoting measures tend to have the least fiscal flexibility left," said Moritz Kraemer, head of European sovereign ratings for Standard and Poor's.
Moody's and Fitch are broadly of the same view.
Dietmar Hornung, a senior analyst at Moody's said that while low growth and inflation was a "major challenge" for some euro zone countries' creditworthiness, "if a country's debt to GDP ratio is above 120 percent and still rising, fiscal space is clearly limited."
European Commission forecasts published earlier this year even before the latest blip in the recovery, put Greek debt rising to 177.2 percent of GDP this year, Italy's to 135.2 percent, Cyprus's to 122.2 percent and Spain's to 100.2 percent.
Among the crisis-hit countries, only Ireland and Portugal are forecast to see modest falls, but in both debt will still be more than 120 percent of GDP. Dublin is also struggling with one of the biggest fiscal deficits in Europe.
"What really matters is credibility," Matt Robinson, a senior credit officer, also at Moody's, said.
"What will be key is that it is clear that the reversal in the debt trajectory (for countries that try and boost growth) has not been cancelled but has just been postponed. But the longer it is postponed the harder it is to sustain credibility."
Euro zone debt crisis r.reuters.com/hyb65p
French gvt debt and deficit link.reuters.com/qum38v
ECB rates, inflation and euro link.reuters.com/jer39v
Draghi speech here
Euro zone ratings factbox
For ratings firms, the worry is that a slackening in the euro zone's austerity drive could see further delays in long-promised moves to cut debts and streamline their economies .
France and Italy are already angling for more time to comply with the European budget deficit rules and France's finance minister said this week low inflation would probably mean it has to scale back next year's budget savings plans.
The worries are putting France at the top of the rating firms' watch list though Italy is also a concern as its economy struggles for momentum.
S&P and Fitch both current have a 'stable' outlook on their respective AA and AA+ French ratings though Moody's, with its AA+ -equivalent Aa1 rating, already has it on a 'negative' outlook.
"French debt to GDP is expected to peak next year at 96-97 percent and we have already indicated that that is very much at the higher end of the range for a country on AA+," said James McCormack, Fitch's global head of sovereign ratings.
"If spending didn't turn out to be growth supportive and the debt dynamics deteriorated further, if it delayed the peaking of debt to GDP ratio and pushed it higher, that could be a concern."
Hornung at Moody's added: "Debt and debt to GDP metrics have been trending up in France for years and fiscal consolidation targets have been revised on an ongoing basis. That is not positive for the credit." (Reporting by Marc Jones; Editing by Toby Chopra)