Jamie Oliver website has been serving up malware since it was hacked in December

Jamie Oliver's website has been compromised by hackers and serving up malware since December, a security firm has found.

The celebrity chef's website, which receives an average of 10 million visitors a month, has now been declared "safe for use", but anyone who visited the website since December 2014 might have been infected by a malicious files embedded into the bottom of webpages on the site.

Jamie Oliver's spokesperson told Business Insider: "The team at jamieoliver.com found a low-level malware problem and dealt with it quickly. The site is now safe to use. We have had only a handful of comments from users over the last couple of days, and no-one has reported any serious issues.

"We apologise to anyone who was at all worried after going on the site. The Jamie Oliver website is regularly checked for vulnerabilities by both our in-house team and an independent third-party and they quickly deal with anything that is found.

"The team is confident that no data has been compromised in this incident but if anyone is worried, do please use the contact form on the site."

The malware was first detected by Malwarebytes during routine research looking into latest security exploits on the internet.

The researchers discovered that malicious code had been injected into the JavaScript on the page that embedded a malicious website directly into the website.

The malicious website contained the Fiesta exploit kit which then tried to attack users' websites if they were not running the latest patched versions of Adobe's Flash, Microsoft's Silverlight and Java.

According to Malwarebytes, once the malware is installed, it hijacks the user' web browser, redirecting it to search results that help earn the hackers income through affiliate schemes.

Users exposed to the malware are also at risk of being duped into installing bogus security updates on their computers, or fake virus warnings urging them to ring what is claimed to be Microsoft technical support.

Security expert Graham Cluley advises that users should make sure that they always have an up-to-date antivirus program running.

It is also a good idea to keep all programs updated with the latest security patches, and also to make sure that you are not using a Windows account with admin privileges.