UPDATE 1-Costco January same-store sales up 8 pct

Feb 2 (Reuters) - U.S. warehouse club operator Costco Wholesale Corp posted a better-than-expected 8 percent rise in January sales at stores open at least a year, helped by higher gasoline prices.

Net sales at Issaquah, Washington-based Costco rose 11 percent to $7 billion in the five weeks to Jan. 29.

Analysts were expecting same-store sales to rise 6.1 percent, including the impact of fuel prices, according to Thomson Reuters data.

Excluding the impact of gasoline prices and foreign exchange, comparable January same-store sales were up 8 percent, Costco said.