Zimbabwe's government says President Robert Mugabe's much-publicised fall in Harare this week was due to "a hump on the carpet," it emerged Thursday.

Mugabe, 90, tripped and fell as he descended steps at Harare International Airport Wednesday on his return from an African Union (AU) summit in Addis Ababa, prompting a flurry of international headlines.

The official Herald newspaper, which is the voice of Mugabe's government, said the red carpet on a flight of steps leading down from a makeshift podium was "poorly-laid."

"Remarkably, the president broke the fall and landed on his knees," the paper said.

Information Minister Jonathan Moyo insisted the president, who turns 91 this month and has just been named AU chair, "managed to break his fall."

"Nobody has shown any evidence of the president having fallen down because that did not happen. The hump on which the president tripped was formed by two pieces of carpet which apparently had not been laid out properly.

"To be honest with you, even Jesus, let alone you, would also have tripped in that kind of situation," he told the Herald.

Normally Mugabe is supported by his wife Grace at many public engagements. But she is still in the Far East recovering from an operation on her appendix.