The Inland Revenue website suffered connection problems today as people tried to beat the deadline for filing tax returns.

The site went down briefly this morning under the weight of applications. The Inland Revenue has said that it is back up and running and users should have no problems.

"HMRC's self assessment online filing service experienced technical difficulties this morning which has meant that some tax payers have experienced difficulties filing online," said a spokesman for the service.

"The system is now rapidly returning to normal levels of service. A record 3.6 million taxpayers have already successfully filed online with 104,000 filing today.

"HMRC takes any disruption of service very seriously and to reflect this no-one who files electronically or by paper by midnight on 1 February will face a penalty."

Nevertheless, accountants in the City have expressed concerns. One had to take tax returns round to the office by hand because the site was running so slowly and messages confirming the receipt of the returns were not being sent.

"I have only had problems with one return I filed online yesterday afternoon, " he said. "It is now very slow, so I am delivering any more by hand in case I don't get notified that the submission failed until after the deadline."

Others complained that the site contained little or no useful information about the problems and had left users in the dark.

This is not the first time the system has had problems. In 2005 the Inland Revenue extended the deadline for returns after the site failed.