A rumour that Parti Pribumi Bersatu Malaysia (Bersatu) chairperson Dr Mahathir Mohamad was admitted to the Intensive Care Unit (ICU) at Putrajaya Hospital is untrue.

"We would like to inform that the message below is totally untrue," Bersatu's media unit said in a Facebook posting tonight.

It was responding to a message that had circulated on social media claiming that Mahathir had faced breathing difficulties.

It claimed that the incident happened while Mahathir was on the way to attend a function in Puchong, Selangor.

The 92-year-old former prime minister is leading the opposition in an attempt to oust his former party Umno and its partners from power.

He had accused Najib Abdul Razak of corruption, a claim the prime minister had denied.

Mahathir had in recent months made frequent public appearances to campaign for the opposition.

He is expected to attend a forum on China's investment at the Kuala Lumpur Selangor Chinese Assembly Hall (KLSCAH) on Thursday.