Despite security concerns, the government has refused to upgrade Internet Explorer 6 from running on most of its computers.
"It is not straightforward for government departments to upgrade IE versions on their systems. Upgrading these systems to IE8 can be a very large operation, taking weeks to test and roll out to all users," said a government statement.
The statement follows a petition sent to Number 10 earlier this year asking the UK government to follow the German and French governments in upgrading the browser.
It is more cost effective to continue using the browser and rely on other measures, such as firewalls and malware scanning software, to protect public sector internet users, the government said.
But despite growing concerns that IE6 attracts cyber attackers because it lacks up-to-date security features, as many as 25% of internet users continue to use the browser.