(Reuters) - Staples Inc , the largest U.S. office supply chain, reported a quarterly profit that narrowly beat analysts' estimates, helped by a slight increase in customer traffic at its North American business.

Smaller rivals Office Depot Inc and OfficeMax Inc also reported better-than-expected earnings in the fourth quarter, raising hopes that the office supply sector was stabilizing after years of sales declines.

Staples however expects a slow growth in the U.S. economy and a soft demand environment in Europe in 2012. It expects full-year sales to increase in the low single-digits and full-year diluted earnings per share to increase in the high single-digits.

Net income for the fourth-quarter rose to $283.6 million, or 41 cents a share, from $274.7 million, or 38 cents a share, a year ago.

Analysts, on average, were expecting a profit of 40 cents a share, before items, according to Thomson Reuters I/B/E/S.

Sales rose to $6.46 billion, while analysts expected about $6.45 billion.

Sales at its North American delivery segment and domestic retail segment, which together account for about 80 percent of the company's revenue, rose 2 percent to $5.16 billion.

Shares of the company closed at $16 on Tuesday on the Nasdaq.

(Reporting by Arpita Mukherjee in Bangalore and Dhanya Skariachan in New York; Editing by Supriya Kurane)