UPDATE 2-H&M sales up in Oct, "Cavalli effect" seen in Nov

(Adds background, analyst comment)

By Simon Johnson and Emma Bengtsson

STOCKHOLM Nov 15 (Reuters) - Fashion retailer Hennes & Mauritz AB (HMb.ST) posted a 15 percent rise in October sales, with analysts hoping a collection by Italian designer Roberto Cavalli will also boost revenue this month.

Sales at comparable stores -- open at least a year -- were up 3 percent in October. A poll of 11 analysts by Reuters forecast a rise on total sales of 14.6 percent according to the average figure. Like-for-like sales were seen up 2.3 percent.

"The figures were not dramatic. I was at 14 percent, so it was a little better than expected," said one analyst who declined to be identified. "It is comforting that they are delivering."

The firm does not give any commentary with its sales figures.

Shares in the underwear-to-suit firm were up 0.73 percent at 411.50 crowns at 0928 GMT against a fall of 1.3 percent in the wider Stockholm market .OMXSPI.

H&M, known for supplying high fashion at high street prices, had a strong fourth quarter so far, with sales in September up 25 percent from a year earlier and like-for-like sales rose 12 percent.

November, the final month in the firm's financial year, is also expected to be strong, boosted by the "king of animal prints" Roberto Cavalli, whose H&M collection went on sale on Nov. 8.

"It was in line or a even a little better than expectations," said Anders Wiklund, analyst at Evli.

"It seems good, if you bear in mind how strong September's figures were. If you think about November, which should see something of a 'Cavalli effect' and more autumn and winter clothes, the quarter looks quite promising."

Shoppers queued for hours outsides stores worldwide to snap up the collection -- available at a fraction of the cost of Cavalli's usual prices -- consisting of 20 pieces of menswear and 25 pieces for women, with lingerie and matching accessories.

The Cavalli collection is one in a series of tie-ups with the stars of the world's of couture and pop, including Karl Lagerfeld, Stella McCartney, design duo Viktor & Rolf, Madonna and Kylie Minogue.

While collaborations with the glitterati only account for a fraction of total sales, they raise H&M's profile and the idea has been taken up by others, such as Sweden's KappAhl, whose advertisements currently feature U.S. actor Richard Gere.

H&M, in business 60 years, said it had 1,490 stores open at the end of October against 1,321 a year earlier.

The firm reports November sales on Dec. 17 with full-year results publihsed at the end of January. (Editing by David Cowell)