Clothing giant Gap Inc has reported a 7% drop in comparable store sales in February, after store closures due to extreme weather conditions led to sales declines at all three of its brands.

The San Francisco-based retailer said comparable store sales at its Gap, Banana Republic and Old Navy brands were down a respective 10%, 7% and 6% during the four weeks to 2 March.

Net sales were down 3.8% to US$929m, from $966m in the same period of last year.

More than 450 stores were closured at some point during the month due to the extreme weather. However, the company said February typically represents the smallest month of the first quarter.

"While February was clearly a difficult month, we remain focused on executing our global priorities," said chairman and CEO Glenn Murphy. 

FBR Capital Markets analyst Susan Anderson said although Gap saw an overall decline, comparable store sales improved in the second half of the month, with week four being the strongest.

"Given the Easter shift from March last year into April this year and storms and cold weather that continued into March, we don't see comp stabilisation as likely until April."