SUBANG JAYA, Sept 9 — Tun Dr Siti Hasmah Mohd Ali is unperturbed by reports that her husband, Malaysia’s longest serving former prime minister Tun Dr Mahathir Mohamad, will be investigated for defamation over remarks he made during the recent Bersih 4 rally.

Speaking to reporters at the Subang airport upon returning from a trip abroad with her husband, Dr Siti Hasmah dismissed the probe as part of life.

"That is politics, that is life," she said when asked for her comment.

Asked if she was prepared for action to be taken against Dr Mahathir, Dr Siti Hasmah declined to comment, saying she was unsure of the details surrounding the investigation.

"I don't know what is going on, so I can't say if I am prepared," she added.

Dr Mahathir and his wife were greeted today by over 100 supporters outside the Subang Airport upon their return from the Czech Republic.

The group of supporters, which also included Malay rights NGO Perkasa, were clad in red t-shirts with the words “Undur Najib” (step down, Najib) imprinted on them.

They also sang a modified version of Michael Jackson's “We Are The World” to show solidarity with Dr Mahathir.

Days after the Bersih 4 rally on August 29 and 30, Inspector-General of Police (IGP) Tan Sri Khalid Abu Bakar announced that the police are investigating Dr Mahathir for allegedly defaming Umno during the event.

The country’s top policeman said the investigation falls under section 500 of the Penal Code, and was kicked off after several Umno division leaders filed police reports against Dr Mahathir over his bribery allegations.

Section 500 of the Penal Code outlines the penalty for defamation, which carries a maximum two-year jail, a fine, or both.

Dr Mahathir had attended the overnight rally on both August 29 and 30.

During a press conference he had held on the second day of the rally at Central Market, Dr Mahathir had demanded that Datuk Seri Najib Razak step down as prime minister.

The fourth prime minister also alleged that several Umno leaders were corrupt and they have not said anything against Najib's administration which has been embattled by various crisis including debt-ridden 1Malaysia Development Berhad (1MDB).

Since then, several police reports against Dr Mahathir have been lodged around the country by a few parties including Umno members.