Johor's Sultan Ibrahim Iskandar has told former prime minister Dr Mahathir Mohamad to silence himself instead of making wild remarks about the 'Bangsa Johor' concept.

This is after Mahathir said in a forum yesterday that Johor nationalism is unhealthy for Malaysia, warning that it can lead to the collapse of the federation.

"It is a figment of Dr Mahathir’s imagination. He is stirring the hornet’s nest and my advice to him is to keep his mouth shut.

"He is going around dividing the people, including the Malays, while I am uniting Malaysians of all races, including the Malays," Sultan Ibrahim is quoted as saying by The Star today.

The sultan added that Mahathir had no right to talk about unity, being a confrontational individual who had caused many divisions.

"Mahathir is the root cause of the present problems in the country. He has no right to interfere in my state. I will not tolerate his antics."

The monarch also chastised Mahathir for being ignorant of the state's history.

Sultan Ibrahim said the term 'Bangsa Johor' was coined by his great-grandfather in 1920 to unite all races in the state "for greater cooperation, harmony and peaceful existence".

"No race or individual was marginalised. He (my great-grandfather) has been proven correct."

The sultan's remark ironically came as Mahathir apologised to Malaysians through a blog post, for making constitutional amendments which curtailed the Agong's authority to veto legislation.