Staples Inc reported lower-than-expected quarterly profit on weak demand for big-ticket items, and forecast full-year earnings well below analysts' expectations, sending its shares down 7 percent.

Assuming modest economic recovery in 2010, the No. 1 office products retailer said it expects full-year earnings of $1.23 to $1.33 a share excluding one-time items. Analysts on average were expecting $1.40, according to Thomson Reuters I/B/E/S.

Last month, smaller rivals Office Depot Inc and OfficeMax Inc posted better-than-expected quarterly results and said sales trends were perking up.

Staples said it expects sales to rise in the mid-single-digit percentage range in the current quarter, and forecast quarterly earnings of 25 cents to 27 cents a share before one-time items. Analysts expect 27 cents a share.

In the fourth quarter, Staples sales at North American stores open at least a year, or same-store sales, were up 3 percent on strong demand for computers, ink and toner. Sales of big-ticket items like business machines and furniture continued to be tepid.

UBS analyst William Truelove said same-store sales fell short of his expectations for a 5 percent increase, but the office supplies seller's North American delivery segment performed much better than he expected.

Fourth-quarter net earnings fell to $238.8 million, or 32 cents a share, from $289.1 million, or 40 cents a share, a year earlier.

Excluding one-time items, it earned 38 cents a share, a penny short of analysts' average forecast, according to Thomson Reuters I/B/E/S.

Sales rose 4 percent to $6.41 billion, beating analysts' average estimate of $6.30 billion.

Staples shares were down 7 percent at $24 in premarket trading.

(Reporting by Dhanya Skariachan; Editing by Derek Caney and John Wallace)