Zimbabwe's President Robert Mugabe has said one of the secrets to his longevity is not to eat until he is full.

The 91-year-old leader, Africa's oldest ruler, made the comment during a televised interview ahead of a birthday party in Victoria Falls thrown for his birthday, which fell on 21 February.

"I do certain things that I believe sustain life," he said.

"I eat well, not filling my stomach, eating foodstuffs that I believe sustain one most. You must eat well, and really not go for food because it's attractive and feed yourself until your tummy is full,"

The leader, often criticised by western countries for his human rights abuses record, has recently been at the centre of an internet craze with hundreds of netziens sharing photoshopped pictures of him falling down the stairs at Harare International Airport.

In his first public comments on the incident, for which Mugabe punished 27 guards accused of failing to prevent him fall, he said: "In the house you slip, your foot is held by a carpet that is misplaced and so on, or you hit it against something and you tumble.

"I would want to see a person who hasn't fallen down. I don't see the reason why anyone should be surprised that the president has fallen."

In January, Mugabe was elected new chairman of the African Union, replacing Mauritania's Mohammed Ould Abdel Aziz.