Twitter said users whose security was compromised will be receiving an email with instructions to create a new password.
"Your old password will not work when you try to log in to Twitter," said Bob Lord, Twitter's director of security.
We encourage all users to take this opportunity to ensure that they are following good password hygiene, on Twitter and elsewhere on the Internet.
Make sure you use a strong password – at least 10 (but more is better) characters and a mixture of upper- and lowercase letters, numbers, and symbols
Twitter also advised that users do not use the same password more than once across other services and accounts.
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Rain spreading eastwards throughout the day.
"His fiancee gave birth this morning, of all mornings! We were scared because we've got Glastonbury tonight", said co-singer Chloe Rhodes.
Festival-goers have been enjoying the second day of the Glastonbury festival.