BERLIN (Reuters) -German high-end carmakers Mercedes-Benz and BMW saw their sales in China dip in the third quarter, the two companies said on Tuesday, with Mercedes hit by supply chain issues and model changes.

Mercedes-Benz's supply issues affected its global sales, which fell 4% year-on-year in July-September, although the company said it was still on track to meet its full-year guidance for flat sales growth.

"Volumes were impacted by a model changeover for the E-Class and a supply-chain bottleneck which constrained availability of the GLC (luxury SUV model)," the company said in a statement as it reported that a fall in global wholesale figures to 510,600 vehicles in the third quarter. Sales in China slumped 12% from a year earlier.

BMW fared better, reporting a 5.8% rise in its global retail sales to 621,699 vehicles in July-September, but said retail sales in China of BMW and Mini models dropped 1.8%.

Carmakers have struggled in China this year with weakened demand and deepening price competition, though passenger vehicle sales returned to growth in August.

BMW said that year-to-date sales in China were up 1.7% despite the drag on sales in the third quarter, while Mercedes-Benz nine-month wholesale figures in the country were at the previous year's level.

Mercedes-Benz said its total sales globally this year so far were up 2% from last year, in line with its full-year guidance for sales at the prior year level.

It does not disclose detailed retailed sales but a spokesperson said they were positive in the third quarter and on a nine-month basis.

BMW said its global retail sales were up 5.1% so far this year.

(Writing by Victoria Waldersee, Miranda Murray, Editing by Friederike Heine and Susan Fenton)