Today GlaxoSmithKline (GSK), the U.K.'s biggest drug company, announced that it has agreed to pay the U.S. government $3 billion to settle several criminal and civil probes related to its sales and marketing practices. The agreement, which the company expects to finalize over the next year, will be the largest pharmaceutical marketing settlement in U.S. history.

The Wall Street Journal reports that GSK's settlement will resolve prolonged investigations of whether it illegally marketed some of its top-selling drugs, including Avandia, Paxil and Wellbutrin, and defrauded Medicaid.

The settlement “is a significant step toward resolving difficult, long-standing matters which do not reflect the company that we are today,” GSK CEO Andrew Witty said in a statement.

“In recent years, we have fundamentally changed our procedures for compliance, marketing and selling in the U.S. to ensure that we operate with high standards of integrity and that we conduct our business openly and transparently.”

Over the past decade, U.S. authorities have increasingly cracked down on drug companies that market drugs for unapproved uses or prioritize profits over patients' interests. As a result, pharmaceutical settlements have dramatically increased.

According to Bloomberg, GSK's $3 billion settlement will surpass Pfizer Inc.'s $2.3 billion settlement in 2009 over its marketing of its Bextra painkiller and other drugs, and Eli Lilly & Co.'s $1.4 billion settlement in 2009 over its Zyprexa antipsychotic drug.