Data protection agencies in Norway, Sweden, Denmark and Finland have quizzed social network giant Facebook on its management of users\' private information, they said Tuesday. \"This is a common action to obtain better knowledge of how personal information is handled by the world\'s largest social network,\" the Swedish Data Inspection Board\'s chief attorney Hans-Olof Lindblom explained in a statement. Norway\'s data protection agency had sent Facebook a list of 45 questions last week on behalf of authorities in all four countries, the statement said. They include queries on the consequences of clicking the \"like\" button to comment on posted items, and the sharing of data that can help determine a user\'s name and address with third parties. The autorities also asked Facebook to explain what it does with photos uploaded to the site, shared items on users\' \"walls,\" and account holders\' stated religious and sexual preferences. The Norwegian Data Protection Agency told Facebook, based in Palo Alto, California, that it had until the end of August to answer each question as accurately as possible, but in no more than 3-4 sentences. \"We have for a long time had a good dialogue with Facebook\'s headquarters,\" Bjoern Erik Thon of the Norwegian authority said in a statement. \"Despite the fact that Facebook is continuously working on improving information to its members, it is unclear what information Facebook collects and how this is used and passed on,\" he said. Facebook head Mark Zuckerberg, who founded the social network in 2004, announced last week the site had reached 750 million users worldwide. Accessing users\' information is indispensable to its revenue model. The site has previously faced lawsuits and been warned by privacy watchdogs over its use of account holders\' data.