Global healthcare giant GlaxoSmithKline Plc (GSK) today said that it had agreed to pay $3 billion to settle US criminal and civil investigations of the company's sales and marketing practices.

The settlement comes after Britain's largest pharmaceutical firm had recorded a legal charge of £2.2 billion ($3.4 billion) to settle additional lawsuits and cost of federal investigation into whether it promoted drugs for unapproved uses, the development and marketing of its diabetes medicine Avandia and potentially influenced doctors.

The probe concerns nine of the company's best-selling products from 1997 to 2004.

The London-based pharma giant said the tentative settlement covers both civil and criminal liabilities.

Shortly after launching Avandia in the market in 1999, SmithKline Beecham's research labs began a study to find out whether the drug was safer for the heart than a competing pill, Actos, made by Japanese drug maker Takeda.

The findings showed that Avandia posed significant heart risks, but within a year of its internal research finding, US drug giant SmithKline Beecham merged with British drug giants Glaxo Wellcome in 2000 to form GlaxoSmithKline.

Although GSK is required in most cases by the US and other countries' laws to post the research results on its website or submit them to drug regulators, the merged entity chose to ignore the law.

GSK then spent the next 10 years trying to cover up the findings as putting a ''safety risk'' tag to the drug would have resulted in $600 million in lost sales from 2002 to 2004 alone.

Avandia was once GSK's top-selling drug until the side effects of the drug came into public domain that led to shrinking global sales of the pill from £1.4 billion in 2006 to £771 million last year.

''This is a significant step toward resolving difficult, longstanding matters which do not reflect the company that we are today,'' said GSK's CEO Andrew Witty in a statement.

''In recent years, we have fundamentally changed our procedures for compliance, marketing and selling in the US to ensure that we operate with high standards of integrity,'' he added.