Mugabe, 94, fails to attend hearing to explain where $15bn of diamonds have gone - but is excused because '9am is a bit too early' for him

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Former Zimbabwean president Robert Mugabe failed to turn up for a parliamentary hearing where he was due to give evidence on corruption in the diamond mining industry.

The 94-year-old, who is in frail health, had been summoned to a session at 9am (7am GMT), today, but when he did not show up, lawmakers had to reschedule the session for Monday.

Committee head Temba Mliswa, an independent lawmaker, told reporters that the parliamentary committee was 'cognizant of the fact that 9am was a bit too early' for the former president to show up.

Former Zimbabwe president Robert Mugabe, above, was summoned to give evidence about diamond corruption, which is alleged to have cost billions of dollars during his rule

He said the Monday session had been set for 2pm, although no-one in Mugabe's office would say whether or not he would attend.

Lawmakers want to question him over his 2016 claim that Zimbabwe lost $15 billion in revenue due to corruption and foreign exploitation in the diamond sector.

'We are not here to humiliate him, we expect him to have enough time to prepare. So on Monday at 2pm we expect him here,' Mliswa said, although he admitted that Mugabe was not legally obliged to attend.

Chiadzwa, where Zimbabwe discovered alluvial diamonds more than 10 years ago, is located in the eastern Marange district

Mugabe ruled Zimbabwe from 1980 until he was ousted from office in November following a brief military takeover. He denounced his ouster as a coup and has not been seen in public since.

His authoritarian regime has been accused of siphoning off diamond profits.

He was replaced by his former deputy Emmerson Mnangagwa, a veteran loyalist in the ruling ZANU-PF party who was backed by senior military officers.

Zimbabwe discovered alluvial diamonds in Chiadzwa, in the east of the country, more than 10 years ago.

Rights groups have accused security forces of using brutal methods to control the scattered deposits.

The parliamentary committee has already interviewed former ministers, police and intelligence chiefs about the mining industry in Chiadzwa.

Zimbabwe has allowed several diamond companies to mine the area – most of them as joint ventures between the government and Chinese firms. But there have been widespread allegations of mass looting.

In July, Zimbabwe is to hold elections, the first since Mugabe was unseated, with ZANU-PF widely predicted to retain power.

Mnangagwa has vowed to hold a fair and free vote, and has pledged to revive the moribund economy by repairing international ties and attracting foreign investment.