Popular social networking site Twitter said that it is already investigating how thousands of accounts were hacked and end up posted online in a file sharing Web site.

This week, hackers affiliated with the hacktivist group Anonymous gained access and published usernames and passwords of users. San Francisco company tweeted that about 35,000 Twitter accounts, not counting about 20,000 that seemed to be redundancies, were posted on the pages of Pastebin.com.

"We're looking into the situation and have pushed out password resets to potentially affected accounts," Twitter said.

Twitter becomes highly popular by allowing people to share short text messages to a lot of people using their smartphones. The company also recommended its users to change their passwords. According to Twitter, the list at Pastebin included spam accounts and incorrect login credentials.

Twitter denied the claims and said that there is no truth behind the reports. Twitter said that the group mostly posted duplicate information or username and password information for suspended spam accounts.

An anonymous Pastebin user posted five extremely long pages of alleged Twitter usernames and passwords to the text storage site on Monday. The hacking news aggregator Airdemon.net reported the supposed breach on Tuesday, beginning to fuel speculation around the web of a massive successful attack on Twitter's servers. Airdemon said celebrity accounts were among those compromised, and also claimed to have information from a "Twitter insider" confirming the attack.