Consumer confidence in the economy increased in September, but spending remained flat, according to Discover Financial Services.

The Riverwoods, Ill., credit card company said Wednesday that its U.S. Spending Monitor rose to 89 in September, from 87 in August. The index was pegged at 100 when it was introduced in May 2007.

One-third of consumers surveyed in September said they felt economic conditions were improving, compared with 31% in August.

Thirty-three percent of respondents rated their finances as "good" or "excellent," the highest in four months and 1 percentage point higher than in August.

Nearly one in five, 19%, said they planned to spend more money this month, down 1 percentage point from August and continuing a four-month decline.

"Consumers definitely feel economic conditions are getting better, but over half still rate current economic conditions as poor," Julie Loeger, Discover's senior vice president of brand and product development, said in a press release. "Combine that with uncertainty as to where their personal finances are headed, and you can see why consumers are still very cautious with their spending intentions."