Former prime minister Dr Mahathir Mohamad has not betrayed Umno by calling on the voters in Pekan to vote out Prime Minister Najib Abdul Razak, party vice-president Hishammuddin Hussein said today.

However. Hishammuddin said, such attacks could damage the party.

"In terms of the party, it is not a betrayal. (But) it should not go on and should not be entertained as it could break the party apart," he told a press conference in Kuala Lumpur.

So far, Hishammuddin added. no damage has been done.

Mahathir ( photo ) is believed to be one of the Umno 7 who are being monitored for disciplinary action.

He has so far remained untouched, despite constantly hammering out at Najib.

However, those who agree with Mahathir are not so safe.

Former MCA president Dr Ling Liong Sik has been told to apologise or face a lawsuit after he supported Mahathir's call for Najib to resign, just one time.

Hishammuddin refused to comment on why Mahathir had been spared.

"You have to ask the lawyer or his client (Najib)," he said.