April 8 (Bloomberg) -- U.S. retailers’ online sales rose 11 percent on average in the first three months of the year, according to a survey by Forrester Research and Shop.org.

Of 80 companies, 58 percent reported their sales increased during the first quarter from the same period a year ago, said Sucharita Mulpuru, an analyst at Cambridge, Massachusetts-based Forrester.

“It seems that consumer confidence is getting better,” Mulpuru said yesterday in a telephone interview. “There is so much price competition out there that you can find great deals. Hopefully the worst is behind us.”

The gains may signal how well online retailers including Amazon.com Inc. are faring following the worst holiday season in at least 40 years. Companies with more than $250 million in online sales annually fared the best, according to the report.

Forrester and Shop.org, a division of the National Retail Federation trade group, asked companies about their first- quarter Web sales in an online survey conducted April 1 and April 2. The average online annual revenue of respondents was $116 million.

To contact the reporter on this story: Joseph Galante in San Francisco at jgalante3@bloomberg.net

Last Updated: April 8, 2009 00:01 EDT