US-based cash-and-carry operator Costco has seen its first-quarter net income rise by more than 17% on the back of higher sales.

For the quarter to 21 November, Costco generated net income of US$312m, an increase of 17.3% on the year.

Net sales were up 11% to $18.82bn. The company said the quarter included sales from its 50%-owned Mexican joint venture as it began consolidating its operations in the country on a prospective basis from the beginning of this fiscal year.

Costco said that, without these sales, the increase would have been 8%.

Comparable sales were up 5% excluding fuel, with a 4% rise in its US operations and a 10% rise internationally.