Internet search giant Google has agreed to pay USD 500 million to settle charges that it allowed Canadian pharmacies to place ads on its website that resulted in prescription drugs being imported from Canada to the US unlawfully.

The Justice Department said the forfeiture is "one of the largest ever in the United States" and represents the gross revenue received by Google as a result of Canadian pharmacies advertising through its 'AdWords' programme, plus gross revenue made by Canadian pharmacies from their sales of controlled and non-controlled prescription drugs to US consumers.

"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 on Wednesday.

The 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," Cole said. Google said it "accepts" responsibility for its conduct, acknowledging that it improperly assisted Canadian online pharmacy advertisers to run advertisements on its site.

Under the terms of an agreement signed by Google and the government, Google must also undertake a number of compliance and reporting measures to insure it does not indulge in such practices in the future.

An investigation by the US Attorney’s Office in Rhode Island had found that Google was aware as early as 2003 that online Canadian pharmacies were advertising prescription drugs to Google users in the US through its AdWords advertising programme.