Swindon Borough Council's website was defaced twice by two different hacker groups at the weekend.

The site, www.swindon.gov.uk, was one of many government and military websites around the world to be defaced on Saturday by a hacking group called Pentaguard, which has been responsible for around 40 hacks over the last year.

Other sites attacked were UK government website www.bseinquiry.gov.uk and Australian government website www.brighton.tas.gov.au.

Swindon's site was then hacked again on Sunday by a group or individuals known as "Krab". The defacement was still visible on Monday morning.

A spokeswoman for the borough council said: "Our ISP now has the website up and running, and we are conducting an investigation into whether there are any gaps in security."

"There is no confidential information on the site," she added.

According to Chris McNab, network security consultant at MIS, the website is running Microsoft's Internet Information Server (IIS) 4.0 on Windows NT.

"If they had installed the latest patches like any good systems administrators, then they wouldn't have had this problem," he said.

The Swindon website joins a long list that have been defaced by hackers exploiting the vulnerability in IIS 4.0. Earlier this month, another borough council - Bury - was hacked.

At the beginning of the year, Boots' website was defaced using the same vulnerability. According to attrition.org, which mirrors compromised websites, NT was the most hacked server operating system last year.