UK National Lottery operator Camelot is urging online lottery players to change their passwords following a security breach.

On Friday, Camelot issued a statement alerting customers that its routine online security monitoring had detected some “suspicious activity on a very small proportion of our players’ online National Lottery accounts.” Camelot has notified the police, the Information Commissioner’s Office and other authorities about the breach.

Camelot said the activity affected only a small number of online lottery accounts – roughly 150 out of 10.5m total registrations had been subject to an unauthorized log-in. “Fewer than 10 accounts” were subject to “some limited activity” after being accessed, but Camelot insists that “no player has seen any financial loss.”

Camelot also insisted that it was taking “all the necessary steps to fully understand” the scope of the intrusion, but had suspended all of the affected accounts and was working with the affected players to reactivate their accounts. As a precaution, Camelot urged all National Lottery players to change their passwords.