Security fears have forced the Inland Revenue to shut its Self Assessment Online service.

An Inland Revenue spokeswoman said that the service was suspended after users reported seeing information about other taxpayers. "The security of our customers' data is of paramount importance to us," she told the BBC.

The spokeswoman stressed that the number of people reporting the problem was small, but that it was decided to temporarily withdraw the service until the glitch is repaired. The Revenue did not say how long this would take.

The problem is something of an embarrassment for Tony Blair's e-government initiative, as it is considering the imposition of fines on companies and individuals who fail to file tax returns online by 2010.

More than 750,000 people filed their returns online last year, but concerns over privacy and security are still seen as an obstacle to wider use of the internet for such tasks.