US warehouse retailer Costco has booked a rise in profits thanks to inflation in gasoline prices and strengthening foreign currencies.

The company today (5 October) announced its fourth quarter and annual results for the year ended 28 August.

Costco’s net income for the fiscal year was US$1.46bn, compared to US$1.30bn for the same period in 2010. In the three months leading up to the year end, net income was US$478m, a rise from US$432m during the fourth quarter of 2010.

Net sales for the year were US$87.05bn, an increase of 14% from US$76.25bn last year, while fourth quarter sales rose 17% to US$27.59bn.

Total US sales rose 10%, a 3% rise on sales growth of 7% last year, while sales from its international division rose by 19%, compared to 16% in 2010.

Costco also announced that it will increase membership fees in the US and Canada from 1 November. The fee increases will impact a little over 22m members, roughly half of which are executive members.

Costco currently operates 592 warehouses, including 429 in the US and Puerto Rico, 82 in Canada, 32 in Mexico, 22 in the UK, nine in Japan, eight in Taiwan, seven in Korea, and three in Australia.