Facebook, the world's largest online social network, has bowed to pressure and agreed to tighten up its privacy policies further.

The company will give its 250 million users more control over the personal information they share with third-party applications such as games and quizzes and will clarify what happens to data when a user deactivates an account.

Currently people who wish to use such third-party software have to agree to share all their personal details with the application. With the changes, the application developer will have to specify which categories of data the software needs, for instance birthdays or geographic location, so users can give explicit permission. Users will also have to specifically approve any access Facebook applications have to their friends' information. Such access would still be subject to the friend's privacy and application settings.

The changes will have significant implications for software developers who have built profitable businesses creating applications for Facebook users. They will need to update their software to comply with the new standards. Facebook said the changes would take up to a year to implement.

The move is in response to Canadian privacy complaints. Last month Canada's privacy commissioner, Jennifer Stoddart, accused Facebook of disclosing personal information about users to the nearly 1 million third-party developers worldwide who create Facebook applications.

Facebook has struggled with communicating its privacy policies to its rapidly growing number of account-holders. Privacy has been a central, often thorny issue because so many people use it to share personal information with their friends and family. As the 5-year-old social networking service has expanded its user base and added features, its privacy controls have grown increasingly complicated.

The company said today that users who want to quit the service have a choice between deactivating their account — in which case the personal details, photos and other information are retained — and deleting the account — in which case all data is erased within a short space of time.

Elliot Schrage, vice president of global communications and public policy at Facebook, said that the changes set a new standard for the social networking industry. The company said that it would actively encourage users to review their privacy settings to ensure that the defaults and selections reflect the user’s preferences.

He said: “Our productive and constructive dialogue with the commissioner’s office has given us an opportunity to improve our policies and practices in a way that will provide even greater transparency and control for Facebook users."

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