The privacy watchdog on Thursday urged the public to protect themselves when using the instant messaging platform WhatsApp, after the accounts of several organisations were hijacked.

The Office of the Privacy Commissioner for Personal Data (PCPD) said that in the past month, five social welfare organisations and schools reported that their WhatsApp accounts had been taken over by fraudsters.

Attempts were made to swindle contacts of the WhatsApp accounts in question, the PCPD said.

"The incidents involved the personal data of nearly 900 individuals and the affected data included names and mobile phone numbers of service users, students, parents of students and/or staff members," the watchdog said.

It urged people to enable two-factor authentication on WhatsApp and to regularly check linked devices, logging out any that are unknown or no longer in use.