However, the ICO does not have the power to block such a move.
“Organisations do not need to get prior approval from the ICO to change their approaches, but they do need to stay within data protection laws,” said Information Commissioner Elizabeth Denham.
WhatsApp has said users could choose not to share account information with Facebook.
The company said the change was part of its plan to explore ways for businesses to send messages using its platform.
WhatsApp said earlier this year that it was experimenting making businesses pay to reach their customers through the service.