PARIS, April 15 (Reuters) - French luxury group LVMH (LVMH.PA) cautioned it might not sustain the powerful first-quarter growth that sent its shares close to a 10-year high this week.

LVMH on Tuesday 13 April posted a 13-percent rise in like-for-like sales in the first three months, twice what investors expected, as retailers stepped up orders for watches, wines and spirits - sectors badly hit by the downturn.

"We might not have during the year the more-than-20 percent, even 30 percent sales growth we saw (at some divisions) in the first quarter," LVMH Chief Executive Bernard Arnault said at the group's annual general meeting on Thursday 15 April.

"We can hope for it but I think we really have to be prudent."

Shares in the world's biggest luxury group soared close to a 10-year high on Tuesday 13 April and were up nearly 1 percent at 90.96 euros at 1435 GMT.

Separately, Bernardette Chirac, the former French first lady, received the backing of LVMH shareholders to join the group's supervisory board.

Chirac was invited to join the board after Helene Carrere d'Encausse, the French historian and academic, declined to join for "personal reasons."

(Reporting by Pascale Denis, writing by Astrid Wendlandt; Editing by David Cowell)