Costco Wholesale Corp.'s net sales in September grew 10.3% to $13.64 billion from $12.37 billion in the same month a year ago.

For the five-week period ended Oct. 7, comparable sales of the warehouse club operator rose 8.4% year over year, with its U.S. business posting the highest growth rate at 10.4%.

Comparable sales in Canada grew 2.9% while sales in Costco's other international markets increased 4.3%.

The company's e-commerce comparable sales went up 28.6% in September.