Twitter has warned its 330m users to change their passwords after a bug was identified that meant passwords could be viewed in plain text on its internal computer system.
The site said it had fixed the problem and that it had seen "no indication of breach or misuse" but advised people to change their password "as a precaution."
"We recently identified a bug that stored passwords unmasked in an internal log," Twitter said in a blog post. "We have fixed the bug, and our investigation shows no indication of breach or misuse by anyone."
Twitter masks passwords through a process of "hashing" where replaces the real password with a random set of numbers and letters in the site's system.
But an error meant passwords were written in full in an internal log before the hashing process was complete.
The company also said it was implementing plans to prevent the bug happening again.
"We are very sorry this happened," Twitter stated. "We recognize and appreciate the trust you place in us, and are committed to earning that trust every day."
It follows the company smashing expectations as it posted $664.9m in first quarter revenue.