Twitter has urged its 330 million users to change their passwords because of an internal bug.
The firm said some users' passwords could be visible on its internal network but said there was no suggestion of misuse or a threat to users.
A message from Twitter Support read: "We recently found a bug that stored passwords unmasked in an internal log.
"We fixed the bug and have no indication of a breach or misuse by anyone.
"As a precaution, consider changing your password on all services where you’ve used this password."
Twitter issued four steps to ensure accounts remain safe:
- Change your password on Twitter and on any other service where you may have used the same password.
- Use a strong password that you don’t reuse on other websites.
- Enable login verification, also known as two factor authentication. This is the single best action you can take to increase your account security.
- Use a password manager to make sure you’re using strong, unique passwords everywhere.
The firm added: "We are very sorry this happened. We recognize and appreciate the trust you place in us, and are committed to earning that trust every day."