Twitter has apologised for a security error that saw large numbers of users' passwords being reset.
Many users of the micro-blogging site received an email earlier this week stating their accounts had been compromised, leading to Twitter resetting passwords.
"Twitter believes that your account may have been compromised by a website or service not associated with Twitter. We've reset your password to prevent others from accessing your account," read the email.
Twitter hasn't provided details of the compromise, but released an apology to affected users, some of whom saw tweets get deleted.
"We're committed to keeping Twitter a safe and open community," read a statement.
"As part of that commitment, in instances when we believe an account may have been compromised, we reset the password and send an email letting the account owner know this has happened along with information about creating a new password. This is a routine part of our processes to protect our users.
"In this case, we unintentionally reset passwords of a larger number of accounts, beyond those that we believed to have been compromised. We apologise for any inconvenience or confusion this may have caused."
The statement added that users should review tips on keeping their accounts secure.