The Prime Minister's Office was not responsible for the cancellation of Dr Mahathir Mohamad's invitation to Tuesday's installation of the new Yang di-Pertuan Agong, Deputy Prime Minister Ahmad Zahid Hamidi said.

It was Istana Negara that decided on this matter, Zahid said.

"Don't blame the Prime Minister's Department or office. If you are unhappy. Please meet (the palace) to get an explanation, don't blame others," he is quoted as saying by Bernama.

On Dec 7, it was revealed that Mahathir had received a letter stating his invitation to the installation of Sultan Muhammad V of Kelantan as Agong was cancelled.

The letter, dated Dec 5, stated that no seat would be provided at the event for Mahathir and that the former prime minister was being informed of this beforehand to spare him any embarrassment if he attended.

The letter bore the signature of the keeper of the ruler's seal Syed Danial Syed Ahmad.

In response to this, Mahathir wrote in his blog that the cancellation could be related to Prime Minister Najib Abdul Razak.

"I apologise for making the wrong assumption (that the palace is above politics). I will note now that Istana Negara belongs to Najib and BN," he had said.