(Reuters) - Automaker Stellantis told its U.S. dealers on Wednesday that its August sales were up 21% from July, and its dealer inventory was reduced for two consecutive months by approximately 10%.

Stellantis National Dealer Council's President criticized CEO Carlos Tavares for the "rapid degradation" of the automaker's brands and urged him to spend more money to clear old inventory, Bloomberg News reported, citing an open letter dated Sept. 10.

The retailers accused the chief of "short-term decision making", which boosted profits last year and padded his compensation which they claim have shrunk market share, the report added.

The automaker also said market share was up 0.7 points in August compared to last month and added that it doesn't believe that "public personal attacks, such as the one in the open letter from the NDC president against our CEO, are the most effective way to solve problems."

The dealership could not be reached out for comment and its President, Kevin Farrish, did not immediately respond to a Reuters request for comment.

Tavares, who described Stellantis' first-half results as "humbling," had said the French-Italian automaker's North American business suffered from a mix of high vehicle inventories, manufacturing issues and a lack of "sophistication" in how it addressed the local market.

In August, Reuters reported that Tavares visited the U.S. to reassure employees,investors and meet dealers in the Detroit area to discuss issues such as reducing inventories and adjusting vehicle production.

Stellantis' first-half operating income fell 40%, mainly due to poor business performance in North America, its profit powerhouse. Vehicle sales in the region for its top brands, Ram and Jeep, have both declined at least 33% from the first half of 2019 to the same period this year, according to research firm Cox Automotive.

(Reporting by Urvi Dugar; Editing by Alan Barona)