Google ( GOOG) agreed to pay $90 million to settle a lawsuit that alleged that the company overcharged advertisers who had paid for bogus sales referrals in so-called click-fraud schemes.

According to the Associated Press, the proposed settlement would apply to advertisers in Google's network during the past four years. The proposed settlement still requires final court approval.

Yahoo! ( YHOO), which is also named in the suit that was filed by an Arkansas retailer on behalf of all Google advertisers, said Wednesday that it intends to fight the lawsuit's allegations, the AP reported.

"Click fraud" refers to users who repeatedly click on specific text-based advertising links -- the links that trigger commissions for Google when clicked -- even though they have no intention of buying from a particular advertiser, causing advertisers to pay for worthless traffic.

The lawsuit alleged Google had conspired with advertising partners to conceal the magnitude of click fraud to avoid making refunds, the AP said.

How large the click-fraud phenomenon among Internet search engines is has yet to determined, causing some analysts to fret that the problem is large -- and could ultimately hinder Google's future profit.

Google executives have repeatedly said the level of click fraud on its ad network is minuscule.

The Wall Street Journal reported that a separate click fraud-related lawsuit was filed against Google in federal district court in San Jose, Calif., last year and is still pending.