The promotion of Johor nationalism is unhealthy for Malaysia and can lead to the collapse of the federation, former prime minister Dr Mahathir Mohammad said today.

While it is within the right of the Johor royalty to promote the idea, Mahathir said, it was only with unity that Malaysia could prosper.

“Well, it is their right to promote the idea. But to me, if each state tries to be separate, then the federation will collapse. We need to work together because only with unity can we prosper.