Google Inc. has agreed to spend $250 million to boost its online advertising and compliance measures to settle a shareholder lawsuit over years-old charges that the search giant knowingly accepted illegal advertisements from online pharmacies, MarketWatch reports.

Google already agreed in 2011 to pay $500 million to avoid Justice Department prosecution on charges that the ads led to illegal imports of prescription drugs and could have put American consumers at risk of taking mislabeled or tainted medicine.

The Justice Department said the forfeiture--which represented the illicit revenue earned by Google and the money earned by the Canadian pharmacies--was one of the largest by a company in the U.S at the time.

The shareholder lawsuit, initially filed in 2011, alleged that Google breached its fiduciary duty to shareholders by accepting the ads.

The settlement, approved in August by a committee of independent Google directors, will be heard in an Oakland, Calif. court on Jan 21.