WASHINGTON (Reuters) - U.S. wholesale inventories edged higher in May despite a big drop in stocks of oil, a U.S. Commerce Department report showed on Wednesday.

Total wholesale inventories increased 0.3 percent to $484.1 billion, matching the median forecast in a Reuters poll of economists.

The government revised slightly lower its estimate for inventory growth in April.

Inventories are a key component of the government's calculation of gross domestic product. Many economists think economic growth slowed in the second quarter, and the data on wholesale inventories appeared unlikely to change that view.

Stocks of durable goods, such as autos, computer equipment and machinery, rose 0.6 percent. Petroleum stocks fell 3.6 percent.

Sales at wholesalers in May fell 0.8 percent, held back by a 4.7 percent decline in petroleum sales. It was the sharpest drop for both readings since March 2009.

At May's pace of sales, it would take businesses 1.18 months to clear their inventories, the highest such reading since July 2011.

(Reporting by Jason Lange; Editing by Andrea Ricci)