MySpace has signed up to Google's new OpenSocial standard, which aims to bring interoperability to web applications that can be embedded in social networking websites.

This means that MySpace will be able to offer all applications created by third-party developers that are compatible with the OpenSocial application programming interface (API).

For developers, the addition of MySpace to OpenSocial is a major step, opening their applications to that social networking site's massive base of users.

On Tuesday, Google confirmed the existence of the OpenSocial programme, which is widely seen as not only Google's strongest move in social networking to date, but also as a response to the rising popularity - and threat - of Facebook.

Although Facebook is the second-most popular social networking site in the world, it is growing faster than MySpace, thanks in large part to the fact that Facebook opened its platform to external developers in May, something MySpace is now copying.

To date, Facebook has about 7,000 applications available for its members. It hasn't said whether it will participate in OpenSocial, although Google has said the door is open.

"Despite reports, Facebook has still not been briefed on OpenSocial. When we have had a chance to understand the technology, then Facebook will evaluate participation," said Brandee Barker, Facebook spokeswoman.

OpenSocial can, in theory, dilute this distinguishing feature of Facebook, by offering a core set of APIs that will let developers write an application once that is compatible with multiple sites.

In other words, OpenSocial seeks to address the inconvenience for developers of having to port applications to different social networking websites.

Other partners in OpenSocial include Oracle, Salesforce, Hi5, iLike, LinkedIn, Slide, Ning, Friendster, Six Apart and Plaxo.

Originally considered of interest only to teens and young adults for communicating with friends, social networking sites have broadened their appeal as they have proven useful for professional networking and business activities.

Within sites like Facebook, a lot of formerly dispersed online activities are united under a single virtual roof, making these sites very attractive for advertisers. Users share a lot of personal information on these sites, making the users easy to target with ads.

There are also question marks about advertising on social networks, primarily because their content is mostly unregulated, and sometimes objectionable, as it is generated by millions of individuals. In addition, social networking sites are under close watch by law enforcement agencies worldwide, because sexual predators have used these sites to stalk and victimise others, including minors.

An earlier sign of Google's sense of urgency about the social networking market was its reported courting of Facebook when the latter was recently seeking a partner to invest in the company and earn a deal to provide advertising to it.

Microsoft eventually won, buying a 1.6 percent stake that values Facebook at an eye-popping $15 billion, although the social networking company reportedly will have revenue of just $150 million this year.

OpenSocial represents "the first release of technical details" for the forthcoming MySpace application development platform, Google and MySpace said.

MySpace, which already runs ads from Google's ad network, has been in talks for the past year about possible collaborations in the area of social applications, the company said.

MySpace's own application development platform will launch "in a few months," but with the OpenSocial APIs, developers will be able to start writing applications for MySpace immediately.

"The applications will be able to be tested within the MySpace environment and then the MySpace Platform will officially go live in the coming months," read a company statement.

Some applications built with the OpenSocial APIs will be available in test mode on the MySpace site prior to the platform's launch.

Google plans to put more information about OpenSocial in this website. There will also be a developer sandbox.