In the latest online security breach, hundreds of Dropbox accounts were leaked on the Reddit website, with hackers threatening to release millions more if they received payment in the Bitcoin online currency.

The hackers, who allegedly accessed the account passwords and log-in names through a third-party service, posted the files in four Pastebin accounts as “teases” for a complete leak of nearly seven million accounts – provided onlookers donate the web-based currency to them.

A message included with this morning’s leak read:

Here is another batch of hacked Dropbox accounts from the massive hack of 7,000,000 accounts. To see plenty more, just search on [removed] for the term Dropbox hack. More to come, keep showing your support.

Reddit-users confirmed that the details published on the site worked at the time it was published, though it remains unclear how many users were actually affected by the leak.

Dropbox, a cloud-storage giant which has its European headquarters in Dublin, responded to today’s leak by stating it was not to blame and that the passwords had been stolen from third party websites.

Speaking to The Next Web, a Dropbox spokesperson said:

“We’d previously detected these attacks and the vast majority of the passwords posted have been expired for some time now. All other remaining passwords have been expired as well.”

This leak of private log-in details is another blow to public confidence in cloud storage, though should also serve as a reminder to users not to employ the same email-password combinations to access multiple online services.

Dropbox is now encouraging its customers to set up two-factor account authentication.

Today's leak is further bad publicity for the storage company after it had to publicly apologise to a group of San Francisco teenagers last week, when a video online surfaced showing Dropbox employees arguing over the rights to play on a soccer pitch in a public park. 

In a statement, Dropbox said: “We love San Francisco and are grateful to call it home. That’s why we were disappointed to learn that a couple of our employees weren’t respectful to this community. The employees involved are embarrassed and have apologized. We’re sorry, and we promise to do better.”