Naomi Campbell’s friend said on Friday that he had handed over three small uncut diamonds to South African authorities after the supermodel testified at the Hague she had given him the “dirty—looking stones.”

Ms. Campbell on Thursday denied knowingly receiving a gift of diamonds from war crimes—indicted Charles Taylor after a celebrity—studded 1997 dinner in South Africa. She testified that two men had knocked on her door late at night and then gave her a pouch with the stones inside.

Jeremy Ractliffe said on Friday that Ms. Campbell had given him the stones as they rode on South Africa’s famed Blue Train on September 26, 1997. He said he had just kept the diamonds until recently, apparently not knowing what to do with them.

“I took them because I thought it might well be illegal for her to take uncut diamonds out of the country,” he said.

In a statement, Mr. Ractliffe said Ms. Campbell had suggested the stones could benefit the Nelson Mandela Children’s Fund, of which he was director at the time, “but I told her I would not involve the NMCF in anything that could possibly be illegal.”

“In the end I decided I should just keep them” and did not report the matter to the fund or anyone else “to protect the reputation of the NMCF, Mr. Mandela himself and Naomi Campbell, none of whom were benefiting in any way,” his statement said.

Mr. Ractliffe, who is now a trustee of the fund, said he has handed the stones over to South African authorities but did not say when that happened.

He told The Associated Press on Friday that he will be a witness at the international war crimes court in the trial of the former Liberian warlord.

Prosecutors had hoped Ms. Campbell would testify that Mr. Taylor gave her the diamonds, which would back up their allegations he traded guns to rebels in neighbouring Sierra Leone in exchange for uncut diamonds, known as “blood diamonds” for their role in financing conflicts, during the country’s 1992—2002 civil war, which left more than 100,000 dead.

Ms. Campbell told that court on Thursday that she did not receive the stones from Mr. Taylor himself. She said they were brought to her room late at night after a presidential banquet where she met Mr. Taylor and was seated between Mr. Mandela and music producer Quincy Jones.

Her testimony did not show, as prosecutors had hoped, that Mr. Taylor traded in so—called “blood diamonds” to arm rebels in neighbouring Sierra Leone.