Facebook is not behind the web search box that has appeared on the pages of some of its users, the company said.

In a statement sent to SearchEngineLand Facebook denied that it had implemented the search box that emerged earlier this week. The search box, which appeared alongside the original search box, fueled speculation that Facebook was making moves into Google's territory with web search.

Not so, says the company, which says it has no plans to implement is own web search engine. Instead, Facebook speculates that the mysterious box is the product of a third-party plug-in or worse, malware.

We believe the second search field or Search the Web box appeared on peoples' accounts as the result of unknown actions by a third party targeting the browser (potentially a browser plugin or malware) unrelated to Facebook  the Facebook spokesperson said.

The company recommends that users scan their systems with anti-virus tools before accessing their accounts.

Though multiple users have reported seeing the search box, its true source still remains unknown.

Facebook has become an increasingly-tempting target for malware creators as the platform's influence and user base have expanded in recent years. The company says that its 500 million users spend over 700 billion minutes a month using the service.