In a video posted on Facebook today, Mahathir said he felt extremely exhausted and had to rest.

“On my doctor’s advice, I went to the hospital (IJN) but it was just a short visit, and I returned soon after.

“I’m now recovering well after receiving treatment and am able to return to my usual routine, including work. I truly apologise for not being able to be there with you yesterday,” he said.

The video included footage of Mahathir visiting Kuala Lumpur International Airport, interacting with the public, and having coffee at the airport today.

Mahathir, who turned 100 last Thursday, was allowed to return home from IJN at about 4.45pm yesterday.

The birthday picnic, held at Putrajaya Lake next to the Perdana Leadership Foundation, was organised in conjunction with his birthday as well as the 99th birthday of his wife, Dr Hasmah Ali, which was celebrated on Saturday.

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

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 9km, he appeared tired and rested briefly on a chair before moving to a table to have breakfast with family and friends.