NEW YORK (Reuters) - Men have long been treated as an afterthought by luxury designers and retailers, given that they spend far less than women on clothes and accessories.

But as men's tastes grow more sophisticated, they are providing a new avenue for much-needed growth in the industry, executives said during the Reuters Global Luxury Summit.

That change is partly being driven by greater competition where men are being challenged to improve their appearance, and a rising professional class in countries like China.

"Men have become far more conscious of grooming, of taking care of themselves, of dressing well. And I think that is something that probably women have driven them into," said Milton Pedraza, chief executive of New York-based Luxury Institute, a consulting firm.

"It is growing in Asia because people are now working in offices and they dress differently. It is more of a longer-term trend," he said.

The sartorial shift has translated into sales gains for top brands.

Coach Chief Executive Officer Lew Frankfort said men's accessories make up about 5 percent of sales now, and his company plans to open more stand alone men's stores.

"We are thinking about urban and nearby suburbs outside major metropolitan areas where there is a more discerning male consumer," Frankfort said.

He added that as Coach becomes a global brand, "The No. 1 opportunity for us is China. We believe the opportunities are boundless in that market."

Oscar de la Renta, renowned for its cocktail dresses and evening gowns, is also thinking of jumping into the fray and developing a line of men's clothing.

But Chief Executive Alex Bolen said the New York-based designer will be careful so as not to disappoint its clients.

"We are continuing to experiment with it. I want to do it, but I want to do it exactly the right way," Bolen said, noting that the company would more likely do some high-end casual wear with a made-to-measure suit service.

Italy's Valentino sees the men's segment as a source of growth. Chief Executive Stefano Sassi said men's items accounted for about 8 percent of sales, a portion that could double within three years.

GROWING, BUT STILL A NICHE

Despite the potential men's luxury offers, it may be limited to a few cosmopolitan centers and to a certain niche group of men, some executives said.

"Putting aside gay men, still -- what is it? 85 percent of the men's underwear in America is bought by women? Wives still buy and still influence most of the purchasing habits for men in America," said William Taubman, chief operating officer of U.S. mall operator Taubman Centers Inc (TCO.N).

Some luxury retailers opening men's stores have done so primarily because of space shortages rather than deliberate strategy decisions, Taubman said.

"Having a separate men's store creates an inconvenience," he added.

At Saks, women's apparel made up about 35 percent of total sales in 2009, more than double men's clothing, and CEO Stephen Sadove said he did not expect that ratio to change much.

Men still lag far behind women in their shopping habits. Online luxury shopping club Gilt Groupe said that 25 percent of its members are U.S. men.

And some despair of ever converting a very large number of khaki-clad, T-shirt loving Americans to a higher sense of style.

"I believe the American male is largely uneducable. We need to focus on the segment of males that have real discerning taste," said Coach's Frankfort.

(Additional reporting by Antonella Ciancio in Paris, editing by Michele Gershberg, Leslie Gevirtz)