Most French voters fear serious damage to the economy if France loses its triple-A credit rating, despite attempts by President Nicolas Sarkozy to reassure them such a blow would be surmountable, a poll showed on Sunday.

Two thirds of respondents said a downgrade could have serious or very serious consequences for the French economy, according to the poll, conducted by firm Ifop and published in newspaper Sud-Ouest Dimanche.

If France's rating were to be slashed, borrowing costs could rise, making it more expensive to finance the country's debt.

France has braced for a downgrade since Standard & Poor's put the ratings of 15 euro zone countries on review on December 5, saying its decision depends on whether euro zone leaders come up quickly with a convincing response to the bloc's debt crisis.

Sarkozy, who has vowed for months to do everything to shield France's AAA rating, changed tack last week and prepared voters for bad news by saying that a downgrade would be surmountable.

Former defence and foreign affairs minister Michele Alliot-Marie said in a radio interview on Sunday that the French government had made a communication error by previously insisting on the importance of preserving the top-notch rating.

Three months ago, the French didn't know what the triple A was, she told Europe 1 radio. I am not a communications expert, but to me this looks like a communications error.

Ratings agency Fitch last week reaffirmed France's triple-A, but dropped its economic outlook to negative from stable, meaning that the rating could be downgraded within two years.

Moody's is also reappraising France's rating as a result of the debt market crisis in Europe.

With the hype and the dramatisation about the loss of the triple A and now the backpedalling ... public opinion cannot make any sense of it and there is now a real concern, Ifop's director Frederic Dabi told Reuters.

(Reporting by Elena Berton and Emmanuel Jarry; Editing by Peter Graff)