The man who had the world's first penis transplant last December is expecting a baby with his partner.

After his penis was amputated in a circumcision-gone-wrong, the 21-year-old South African became the first man to receive a penis transplant after a successful, groundbreaking nine-hour operation at the Tygerberg Hospital in Cape Town.

Professor André van der Merwe, who lead the team of doctors who performed the surgery, said news the patient was now set to become a father confirmed the operation's success.

"Our goal was that he would be fully functional at two years and we are very surprised by his rapid recovery," he said.

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He said a paternity test would not be performed as there was no reason to disbelieve the patient.

Professor Merwe, who said he was delighted, said the news was a milestone for the man and was keen for similar operations to be carried out in the future.

The operation was performed as part of a pilot study by the hospital and the University of Stellenbosch to help the 250 or so young South African men who lose their penises each year after botched coming-of-age rituals.

The men, mainly from the Xhosa tribe, mark their passage into manhood by shaving their heads and smearing themselves with white clay from head to toe, living in special huts away from the community for several weeks, and then undergoing ritual circumcision.

But in May 2013, more than 20 youths died after initiation rituals in the northerly Mpumalanga province, prompting rare cross-party calls for reform of a traditional practice.

A few months later, police made several arrests on suspicion of murder after 30 young men died in the rituals in rural Eastern Cape.

Unlawful circumcisions have been known to injure up to 300 young men across the province in the space of a week.

Professor Merwe hoped penis transplants would eventually also be offered to men who have lost their penis from cancer or as a last resort for severe erectile dysfunction.

Nine more patients have been lined up to have the operation.

BBC/Reuters