A spokesman for the police special investigations unit said Jeremy Ractliffe handed over the stones on Thursday and that the police have given them to the local diamond regulation authority for examination.
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 hosted by Nelson Mandela. She testified that two men had knocked on her door late at night and then gave her a pouch with the stones inside.
Ractliffe said Friday that Campbell had given him the stones as they rode on South Africa's famed Blue Train on Sept. 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, Ractliffe said 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. Ractliffe is now a trustee of the fund.
Musa Zondi, a spokesman for the police special investigations unit in South Africa, said officials could only decide whether to pursue a case after the local diamond regulation authority examined the stones.
"They must say if they are diamonds in the first place and where they come from, and that will determine whether they are blood diamonds or not," Zondi told The Associated Press.
Ractliffe 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 Campbell would testify that Taylor gave her the diamonds, which would back up their allegations he traded guns to rebels in neighboring 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.
Campbell told that court Thursday that she did not receive the stones from Taylor himself. She said they were brought to her room late at night after a presidential banquet where she met Taylor and was seated between Mandela and music producer Quincy Jones.
Her testimony did not show, as prosecutors had hoped, that Taylor traded in so-called "blood diamonds" to arm rebels in neighboring Sierra Leone.