UK National Lottery operator Camelot has warned its digital customers that their personal data may have been compromised.

This week, Camelot issued a release stating that its online security monitoring had revealed “suspicious activity on a very small proportion of our players’ online National Lottery Accounts.” Camelot said around 26,500 accounts were unlawfully accessed, and the company is requiring these players to reset their passwords.

Camelot said fewer than 50 of the affected accounts saw “some activity take place within the account since it was accessed.” Some of the personal details in these accounts were changed, although Camelot suggested that the changes may have been made by the players themselves. These accounts have been suspended until Camelot can contact each customer to work with them to reactivate the account.

Camelot said it’s still trying to ascertain the full extent of the digital intrusion, although it suggested that email addresses and passwords may have been acquired from hacking another website for which National Lottery customers used the same details.