Senior management has now blocked nearly 2,000 internet sites and has threatened officials with the sack for misusing computers. Last week Computer Weekly revealed that tax staff had been breaching the Data Protection Act and the confidentiality of taxpayers by browsing accounts without authorisation.
Only about 2,500 end-users, out of more than 60,000 in the department, have been given access to the internet as part of the trial.
The Inland Revenue's internal publication Revenews said, "Some internet activity is causing concern." It quoted Tony O'Dwyer of the conduct and discipline section of the Revenue's human resources department as saying that sites some officials had sought to visit were "a breach of Inland Revenue values" and were illegal.
"The system automatically logs all internet sites visited and by whom, and we check these regularly. As a result, we have blocked nearly 2,000 sites. If there is evidence of repeated visits, or attempted visits to unacceptable sites, we will investigate further," said O'Dwyer.
He said some staff are "clogging up the system and wasting Inland Revenue time".
In 2001 there were 226 disciplinary cases of computer misuse that led to Inland Revenue staff being fined, reprimanded, receiving a bar on promotion, having their positions downgraded or being dismissed.
The Revenue's senior managers admit that the department has more than one security policy for the use of computers, which could confuse some staff. The board has asked HR to draw up a single security policy.
The Revenue has also warned that it may monitor the contents of internal e-mails if it suspects that their contents are obscene or abusive.