Companies bidding on phrases which are already ranked highly on search engines may impact upon their organic results, it has been suggested.

Writing for Search Engine Land Bill Slawski points to a newly granted Microsoft patent which discusses a possible correlation between the appearance of paid and organic search listings for the same website page on a single set of search results.

According to the United States Patent and Trademark Office, the Microsoft system could remove "unnecessary multiple references to a common resource", causing more than one link to the same page to be removed from search results - a move which could impact on advertisers looking to make best use of search engine optimisation.

Microsoft added that as a result search engines could show "a greater number of unique display URLs than would otherwise occur absent [of] this form of filtering".

Slawski also claimed that advertisers could find their organic listings removed from search results if they also have a paid listing advertisement directing users to the same page.

However, Google's Susan Minniear claimed firms should always invest in paid search advertising, even if their branded keywords are constantly ranked high in organic searches.

She claimed that paid ads can help companies manage their marketing campaign and target specific consumers.