The study found that the growth in the number of online banking customers at the 10 most-visited online banks softened in 2007 compared to the previous year.

Over 47 million Americans logged on to a liquid online account at one of the country's top ten banks in Q4 2007, an increase over the same period in 2006. But ComScore says from Q2 2007 to Q3 2007, the number of Web banking customers who logged on declined by nearly one per cent, which was the first quarterly decrease seen in the industry in the past five years.

Furthermore, although Q4 2007 saw a 0.9 percent increase in quarterly growth, it was just half the previous year's fourth quarter growth of 1.8 percent, says ComScore.

The study also examined customer satisfaction with online services and a survey of over 2500 American adults found 72% are "highly satisfied" with their primary online bank - a two per cent rise on the previous year. Banks scored higher than credit card companies (65%) and brokerage firms (70%) for customer satisfaction.

However, with the market becoming saturated comScore says banks need to introduce new features to attract and maintain customers.

"After several years of strong growth in the number of users of online banking services, it appears the market is entering its next phase," says Brian Jurutka, vice president, comScore. "As a result, many of the top banks are realising that customer servicing is of increasing importance in this competitive market and are therefore investing resources into online service enhancements, as well as mobile banking."

A quarter of respondents said they are interested in the ability to chat online with their bank, while 23% would consider having a widget to display their account balance. Around 14% said they would be interested in blogging.

Meanwhile, a quarter of respondents are interested in mobile banking - a slight rise on the previous year - with obtaining account balance information the biggest draw.

Jurutka says customer receptivity to chats and widgets "is consistent with general online industry trends".

"Consumers are increasingly relying on emerging media in many aspects of their online lives, so it's natural that they would want their online banking experience to conform to these expectations," says Jurutka.

But Jurutka warns that while consumers express an interest in these features, "observed behavioural data shows a much lower adoption rate".

"This may be due to the fact that many banks have not yet developed capabilities to adequately match consumer expectations, which provides additional opportunities for banks to satisfy their customers," he says.

A 2006 study by Gartner called on firms to adopt Web 2.0 applications such as wikis, podcasts and blogs in order to improve cross-enterprise collaboration and deliver personalised information to clients. Since then some banks have tried out the technology but take-up has been sluggish.

A separate UK study released by IT specialist Conchango last year found that fears over brand damage are preventing Britain's major retail banks and building societies from implementing Web 2.0 applications.