The Inland Revenue was forced to shut down its internet tax self-assessment service earlier this week because of security breaches.

"Several people were using the self-assessment online service over the weekend when they noticed the details of other filers and reported the problem to us. As a result, we temporarily shut down the system and are now working around the clock to get to the bottom of the problem," said an Inland Revenue spokesman.

The Inland Revenue declined to give details of the personal data revealed or how many people had confidential information made public. It was also unable to estimate how long it will take to repair the problem and get the service back online but did say the security breach was in an electronic form used for filing taxes online.

"There are several commercial products that are available for filing taxes over the internet and we are still accepting those," the spokesman said.

Last year, 76,287 returns out of a total of just under nine million UK tax returns were completed online. The Inland Revenue's self-assessment service accounted for 90 percent of the returns filed online and, so far this year, almost 11,000 people have used it.

The government has been encouraging people to file their taxes online. The Inland Revenue recently sent out flyers in an attempt to allay public concerns over security issues and urging taxpayers to switch over to the online system.

Chancellor Gordon Brown announced government plans in April for getting businesses and individuals to file tax returns online by 2010. This could possibly include imposing fines those who fail to use the internet to file.

Accounting company Ernst & Young LLP conducted an internal review of the Inland Revenue's online system soon after it went public about two years ago. Security concerns kept it from recommending the system to its customers and from using it itself, said Ernst & Young spokesman Rayner Peett.

"Our review turned up a number of concerns . . . Such a system has to be able to guarantee the absolute security of confidential information and we didn't feel the IR's system could do that . . . We hope this breach in security will goad the government into doing whatever is necessary to assure the security and confidentiality that taxpayers require," Peett said.