Luxury goods group Richemont SA has continued to post double-digit sales rises despite the economic slowdown - but the company is warning that the good times may not last.

Executive chairman Johann Rupert told the company's AGM in Geneva that for the five-month period to the end of August, sales were up 11% on a reported basis, or 18% at constant exchange rates.

The increases follow the company's earlier reporting of first quarter sales up 13% on a reported basis, or 20% at constant exchange rates.

The strongest growth came from jewellery businesses Cartier and Van Cleef & Arpels.

But leather and accessories were down 5%, "reflecting the more difficult trading environment in this area of the market", said Rupert.

Other businesses, including fashion label Chloé, reported growth of 24%, boosted by the impact of recent acquisitions.

Sales increases in Europe (17%) and Asia-Pacific (19%) were partly offset by an 8% decline in Japan, while sales in the Americas were flat, largely due to the weakness of the dollar. Underlying sales there were up 14%.

However, Rupert said there were signs of a slowdown in the US, thanks to the economic difficulties there.

"The impact of the global financial crisis, the high rates of inflation and high commodity prices on our business is difficult to predict," Rupert said.

"To date, the top end of the luxury market - where Richemont's Maisons are predominantly positioned - has not been affected. That is not to say that Richemont is immune from a slowdown, but we do believe that we are better-placed than many to weather difficult times ahead."

The company will report its six-monthly results to 30 September in November.