WASHINGTON - Online search engine Google Inc. has agreed to pay $500 million to settle claims that it allowed online Canadian pharmacies to place advertisements targeting consumers in the United States, US Justice Department announced Wednesday.

The settlement, one of the largest ever in the United States, represents the gross revenue received by Google as a result of Canadian pharmacies advertising through Google's AdWords program, plus gross revenue made by Canadian pharmacies from their sales to US consumers.

The advertisements led to illegal imports of prescription drugs into the country, the Justice Department said.

The shipment of prescription drugs from pharmacies outside the United States to customers in the United States typically violates the Federal Food, Drug and Cosmetic Act and in the case of controlled prescription drugs, the Controlled Substances Act.

Google was aware as early as 2003, that generally, it was illegal for pharmacies to ship controlled and non-controlled prescription drugs into the United States from Canada.

"The Department of Justice will continue to hold accountable companies who in their bid for profits violate federal law and put at risk the health and safety of American consumers," Deputy Attorney General James Cole said in a statement.

"This settlement ensures that Google will reform its improper advertising practices with regard to these pharmacies while paying one of the largest financial forfeiture penalties in history," he said.

Google had previously set aside that amount for a possible settlement over its advertising practices, according to a regulatory filing in May.