She has hit headlines for marital strife, designer dresses and her surprise role as an envoy to Libya, but France's first lady, Cécilia Sarkozy, is now under scrutiny over her tonsils.

The French president, Nicolas Sarkozy, on holiday in the US, attended an informal family picnic at George Bush's retreat in Maine on Saturday, sharing burgers in the name of Franco-US relations. But his wife was unexpectedly absent, blaming a severe throat ailment that prevented her making the one-hour trip from the Sarkozys' rented villa in New Hampshire.

The Bushes were sympathetic. But the fact that Mrs Sarkozy was spotted shopping with friends on both Friday and Sunday raised eyebrows in France.

"Cécilia has set a new record for making a swift recovery," a news reader said dryly on France Inter radio today. "Cécilia coughs, France and America catch a cold!" warned the regional paper, La Nouvelle République du Centre-Ouest. The financial daily Les Echos said the incident heightened her reputation as "secretive, unpredictable, even disconcerting".

Questions over Mrs Sarkozy's official role have abounded after her unexpected foray into international politics by apparently helping to broker the release of Bulgarian medics imprisoned in Libya.

The Elysée has said her role and aims will be outlined in the autumn. She said two years ago: "I don't see myself as a first lady. It bores me. I'm not politically correct." Talking to reporters last month, Mr Sarkozy said: "At the end of day, my only real worry is Cécilia."