The strength of Umno lies not with individuals such as the president, but with its members, said party president Najib Abdul Razak.

Thus, he said, the party will be just fine without its former stalwart Dr Mahathir Mohamad.

"In fact when the late-Onn Jaafar, the founder of Umno, quit the party, Umno did not die just like that, but this party remained prosperous until now.

"That is why, when Mahathir said he would not return to Umno, go ahead... it is not a problem for Umno," Najib was quoted as saying by Bernama.

He was addressing delegates at the Lipis Umno division annual assembly in Pahang today.

"I am not being arrogant, I am not insulting him (Mahathir) because I realise and humble myself that my strength today is because of the support of more than three million members of this party," he added.

Mahathir quit Umno last year and went on to form Parti Pribumi Bersatu Malaysia (Bersatu). Following this, he was made the chairperson of the main opposition coalition Pakatan Harapan.

The nonagenarian is now one of Najib's most ardent critics, constantly harping on issues such as the 1MDB scandal in an effort to rally supporters against BN.

List of Dr M's failures

Najib openly hit back at the former premier's criticisms today, saying the latter himself had cost the country billions in losses.

"His Proton failed, and we had to save it by giving RM1.5 billion and adding another RM1.5 billion. MAS, Perwaja, Bakun dam and many others made losses.

"During his tenure, there were RM33 billion in losses due to the forex (scandal), who is going to answer for that? He keeps talking about 1MDB when we actually have land and assets that can attract investors and make a profit.

"But this RM33 million in losses, who is going to answer? Mahathir is going to answer? Answer at the Royal Commission of Inquiry (RCI)," he said.

Mahathir has said that the forex RCI was an attempt to discredit him prior to the next general election.