His aide said Mahathir, 100, is currently under observation for fatigue related issues.

“He is resting but we expect him to be back home by this evening,” said Sufi Yusoff, a spokesman for Mahathir’s office.

This morning, Mahathir left a picnic in Putrajaya earlier than expected after reportedly feeling slightly fatigued.

The event, held at Putrajaya Lake next to the Perdana Leadership Foundation, was organised in conjunction with his 100th birthday celebration on July 10, as well as the 99th birthday of his wife, Dr Siti Hasmah Ali, which was celebrated yesterday.

Mahathir drove to the event himself before cycling around the lake on a tandem bicycle, accompanied by security officers.

However, after completing a ride of about 8-9km, he appeared tired and rested briefly on a chair before moving to a table to have his breakfast with family and friends.

Mahathir left the event at about 10am. According to a source, he and his wife left early to return home and rest.

His son, Mokhzani, who was also at the event, said Mahathir was tired after having attended another event the day before and not getting much sleep.

“This morning, he went straight into a fairly long cycling session, so he felt a bit tired. But after having some breakfast, a few traditional cakes and coffee, he was back feeling refreshed,” he said.

More than 500 people were believed to have attended the event, and many of them brought a variety of food for the picnic.