Washington, Jan 12 : Yahoo has said that users outside Europe may have been affected more in the ad-related malware attack that seems to have farther reaching effects than expected.

According to the post updated on the Yahoo Help site, more than 2 million PCs could have been affected and chances of Yahoo users' personal data being compromised are high.

There are speculations that the attack may have actually begun four days prior to the estimated day (between December 27 to January 3), Cnet reported.

The website stated that the malicious advertisements were on European sites and Yahoo users outside Europe, who accessed these sites, may also have been impacted

FoxIT, a Netherlands-based security company had previously said that the users in UK, France, and Romania were the hardest hit.

Meanwhile, Yahoo assured that people using Macs or mobile devices were not susceptible to the attack and issued guidelines on its website to prevent users from redirecting to malware affected sites.( ANI)