Twitter said that it mistakenly reset the passwords of many of its active users while conducting routine security screening to identify accounts that may have been compromised.

"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," Twitter said in its blog on Thursday. "In this case, we unintentionally reset passwords of a larger number of accounts, beyond those that we believed to have been compromised."

Twitter declined to say how many Twitter accounts were affected by the error and also clarified that there had not been a security breach.