Amazon.com Inc. on Tuesday reported that sales rose by 26 percent in the second quarter, but profits fell by nearly a third, due to an income tax expense.

The Seattle-based online retailer said net income for the period ended June 30 was $52 million, or 12 cents a share, compared with a net income of $76 million, or 18 cents a share, in the same period a year ago. Profits fell because of $56 million in income tax expense, compared with $5 million a year ago.

Revenues, however, increased to $1.75 billion in the quarter from $1.39 billion last year.

Jeff Bezos, founder and chief executive of Amazon.com, said sales were helped by the company''s 5-month-old Amazon Prime program, which offers unlimited, express two-day shipping for $79 a year, with no minimum purchase requirement.

"Though expensive for the company, Amazon Prime creates a premium experience for customers who join, and as a result we hope they''ll purchase more from us in the long term," Bezos said in a statement.

For the third-quarter, Amazon.com forecast net sales of between $1.76 billion and $1.91 billion, or between 20 percent and 31 percent higher than the same period last year. For the full year, net sales were expected to top 2004 by between 20 percent and 25 percent, or from $8.3 billion and $8.7 billion.