Cloud storage site Dropbox has moved to deny claims it has been hacked after an anonymous account posted what it claims is the username and passwords of hundreds of the site's users.

An anonymous post to website Pastebin, traditionally used to save text users would like to paste elsewhere later, contained a list of hundreds of email log-ins and passwords the hacker claimed were linked to Dropbox account.

The post claimed that more than 6.9 million Dropbox accounts had been hacked, and that more would be posted.

The hacker asked for donations in digital currency Bitcoin in exchange for revealing the alleged flaws in Dropbox's security, as well as revealing more account details in the future.

"As more BTC (Bitcoin) is donated, More Pastebin pastes will appear", said the post.

However, Dropbox has moved to deny that its service has been compromised. Anton Mityagin, who is part of Dropbox’s security team, said it was an attempt to gain money from stolen data found elsewhere online.

"Recent news articles claiming that Dropbox was hacked aren't true. Your stuff is safe," he said.