ZURICH, July 21 (Reuters) - Demand for Swiss watches tumbled by nearly a third in June as the rich curbed their spending on pricey, gold timepieces.

Omega Speedmaster from the Swatch Group

The most expensive watches, costing more than 3,000 Swiss francs ($2,793) at export price, were hit hardest with the number of units sold falling some 40 percent. Watches made from gold suffered a particularly sharp decline in demand.

Demand for timepieces slipped 26 percent in the first six months of the year and the Swiss watch industry is facing its steepest drop in demand in some 20 years as job losses and the crumbling of investment portfolios have spooked consumers.

"The situation on the main markets deteriorated in June. Hong Kong reported an above average drop. Results in the U.S. fell by half," the Swiss Watch Federation said on Tuesday 21 July.

The decline of the main European markets was more moderate, but still reached double-digits, it said, adding that the decline in Japan also gathered pace.

Demand for watches costing between 200 and 500 francs ticked higher in June, reversing the recent downward trend, while the number of wristwatches selling for less than 200 francs fell by 16 percent.

"The rate of decline has deteriorated rather than stabilised, suggesting that destocking continues in a number of countries," said Helvea analyst Alessandro Migliorini in a note.

"The high end is now suffering the most whereas it is interesting to note that the 200-500 franc price category has done relatively well," Migliorini said.

"In theory, this suggests that the Swatch Group should be more resilient than a number of its competitors."

By 0858 GMT, shares in Swatch Group (UHR.VX) were 1.2 percent higher at 176.10 francs, while rival Richemont (CFR.VX) was down 0.3 percent at 24.54 francs. The DJ personal and household goods index was 0.2 percent higher.SXQP.

The drop in demand for Swiss watches comes as Swiss exports tumbled nearly a quarter in June, extending a slide that has wiped out three years of trade growth.[IDn:LH710774] (Reporting by Katie Reid)