The bizarre fallout from Sonny Bill Williams's bout with Francois Botha has taken another twist, with the South African claiming his pre-fight urine test was taken by a family member of Williams's manager.

Fairfax has obtained Botha's pathology report from the test, which was taken three days before his loss to Williams.

The pathology report shows traces of the banned stimulant phentermine.

Botha's camp have maintained his innocence since news of the positive test came to light and on Monday, Botha told a New Zealand television station the test was taken by the brother of Williams's manager Khoder Nasser.

However, Fairfax is reporting the name of the doctor who took the test appears on Botha's pathology report and he is not related to Nasser.

Botha's manager Howard Goldberg has confirmed Botha's allegation.

"Frans has told me it was a member of Nasser's family that took the urine test for him," Goldberg told News Ltd.

"I was not in the room with him (for the test).

"If Frans has been on drugs I would be very disappointed but even if this test ... is real then it would be inadmissible as it was not conducted by a legitimate body.

"Frans has gone to a lab here in Durban today to have his urine tested and we will be able to clear his name with that."

Nasser has refuted Botha's claim.

"The pathology company is a very reputable company in Australia," Nasser told News Ltd.

"Frans went along with the local commission to do his blood tests for hepatitis and at the same time said he would do a voluntary urine test.

"I don't know why he volunteered to do it."

The test was conducted independently and not by the Australian Sports Anti-Doping Authority.

The test result has been sent to WBA headquarters in Panama for further analysis.

Williams's win over Botha last Friday night was surrounded in controversy when the fight was stopped after 10 rounds despite originally advertised as a 12-round bout.

"I had Williams in all sorts of trouble in the 10th round and there was no way he was going to last one more round, let alone two, he was out on his feet," Botha said of the fight.

"It was a disgusting state of affairs and it amounts to match-fixing. I have asked my manager to apply to have the bout expunged from my record."

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