Image caption The site has made a series of changes to its privacy settings in recent months

Facebook has begun to roll out changes to the site in its efforts to appease critics of its privacy practices.

The change means that games and applications installed on a person's profile must specify what personal information they will access and use.

The changes were first announced in 2009 in response to work with the Canadian Privacy Commissioner.

In May 2010, the site was forced to overhaul its privacy settings in response to user concerns.

The moves were welcomed by privacy advocates.

"It is encouraging to see Facebook act on its stated commitment to providing users with simple but real control over their information," said the US Center for Democracy and Technology. "The changes Facebook announced today represent an important and positive step for the company."

Single control

The changes will apply to all third-party applications and games that a user installs on their profile.

"With this new authorisation process, when you log into an application with your Facebook account, the application will only be able to access the public parts of your profile by default," said the firm's Bret Taylor in a blog post.

"To access the private sections of your profile, the application has to explicitly ask for your permission."

A user will be presented with the permissions box every time they install a new application or first log in to an external website with their Facebook account.

The social network currently offers more than 550,000 applications, including games such as the popular Farmville.

The site says that more than 70% of its 500 million users use an application every month.

Last month it was forced to simplify its privacy settings after storms of protest from users and privacy groups.

The new system brings all of the site's settings into one page, with suggested default settings.

When they were introduced, Facebook founder Mark Zuckerberg admitted the older settings had become too unwieldy and difficult for users.

"The number one thing we've heard to that the settings have gotten complex and hard for people to use," he said at the time.