Microsoft, the world's largest software maker, has said it is cooperating with New York Attorney General Eliot Spitzer in a bid to crack down on spam.

Microsoft General Counsel Brad Smith and Spitzer were set to hold a joint news conference in New York on Thursday, said Sean Sundwall, a Microsoft spokesman.

"I can confirm that the announcement will be about cooperation with the New York Attorney General on spam," Sundwall said.

Microsoft, which has gone on the offensive against email advertising touting everything from get-rich-quick schemes to pornographic websites, is developing anti-spam technology and also waging legal war against spammers.

Microsoft's Smith has said that Microsoft would work to fight against spam on all fronts, including its ongoing efforts to protect consumers by using better technology such as blocking and filtering tools, and also collaborate with other internet businesses.

In June, Microsoft filed 15 lawsuits in the United States and the United Kingdom against spammers, claiming that they were responsible for flooding its MSN internet service with more than 2 billion unsolicited email messages.

Microsoft Chairman Bill Gates vowed in an open letter in June to make the fight against spam one of the number one software maker's top priorities.

On Tuesday, US President George W. Bush signed the first national anti-spam bill into law, outlawing some of the most annoying forms of junk email and setting jail time and multi-million dollar fines for violators.