Web search leader Google  has signed on MySpace, the world's largest social network, to its platform allowing outside software developers to write programs for social web sites, the companies said on Thursday.

The addition of MySpace gives the Google platform greater strength against fast-growing Facebook, which opened up its site to developers in May and has seen its user base grow to more than 48 million people since then.

Google unveiled its OpenSocial platform earlier this week, saying it would give outside developers tools to write programs for any of its social network partners.

This will eliminate the need for small startups or even one-person shops to customize their programs for each site.

"OpenSocial is going to become the de facto standard (for developers) instantly out of the gates. It is going to have a reach of 200 million users, which is way bigger than anything else out there," Chris DeWolfe, chief executive and co-founder of MySpace, told reporters.

Google and MySpace said they had been working together on the project for more than a year. News Corp.-owned  MySpace has some 110 million users worldwide.

Google had already disclosed that social networks such as LinkedIn and Friendster joined the program as well as some of the biggest independent developers on Facebook.

Google lost out to rival Microsoft  last week, when the software maker took a minority investment position in privately held Facebook and shored up its position as the site's advertising delivery partner. The deal valued Facebook at $15 billion.

Google executives said the company had also reached out to Facebook, and hundreds of other sites, about joining its OpenSocial platform. Facebook representatives had no immediate comment.