Microsoft Corp, Google Inc and Yahoo Inc agreed to a settlement worth $31.5 million to resolve claims they promoted illegal Internet gambling, the Justice Department said on Wednesday.

All three companies were accused of receiving money resulting from online gambling business to advertise illegal betting between 1997 and 2007.

"These sums add to the over $40 million in forfeitures and back taxes this office has already recovered in recent years from operators of these remote-control illegal gambling operations," said U.S. Attorney Catherine Hannaway in St. Louis, Missouri, according to Reuters.

The settlements stem from an investigation into illegal online gambling by U.S. attorney Catherine Hunnaway, the Federal Bureau of Investigation and the Internal Revenue Service.

Microsoft has the biggest amount to pay worth $21 million, from which $4.5 million will go to the U.S. government and $7.5 to the International Center for Missing and Exploited Children. The company also has to provide a $9 million online public service advertising a campaign, which supports the idea that online gambling is illegal at those of college age and younger.

Microsoft’s representative, David Bowermaster said the company had stopped accepting ads from online gambling sites nearly four years ago.

“Although Microsoft stopped accepting ads from sites associated with online gambling nearly four years ago, this agreement reflects our ongoing commitment to online safety," he said.

Yahoo has to pay $7.5 million for allegedly receiving payments over a 10-year period from online-gambling companies for advertising their Websites. From this amount, $3 million go to the U.S. government and $4.5 million are destined for online ads supporting the illegality of online gambling.

Google has to pay the smallest amount worth 3 million, the department said. The company said in a statement that had stopped voluntarily carrying such ads in April 2004