(CNN) -- British supermodel Naomi Campbell has asked to postpone her testimony at the "blood diamonds" war crimes trial for the former Liberian president, the chief prosecutor's office said Thursday.
Campbell did not want to be involved in the trial but was subpoenaed on July 1 to appear at the tribunal for Charles Taylor, who faces war crimes charges over a brutal conflict in Sierra Leone that was fueled by rough diamonds, also known as blood diamonds or conflict diamonds.
Witnesses have said Taylor gave Campbell a diamond.
Campbell was scheduled to appear July 29 at the trial in The Hague, Netherlands. She has requested to postpone her testimony to August 5, the prosecutor's office said. The judge will make a decision on the request Monday.
Prosecutors had rested their case against Taylor in February 2009. They asked to reopen it specifically to call Campbell, as well as actress Mia Farrow and a witness named Carole Taylor, court papers show.
Prosecutors said they learned in June 2009 that Taylor had given the supermodel a diamond in South Africa in 1997. Farrow confirmed it, they said.
When arguing to reopen the case, prosecutors said Campbell's testimony would prove that the former president "used rough diamonds for personal enrichment and arms purchases," according to papers filed with the U.N.-backed court.
Taylor, 62, was president of Liberia from 1997 to 2003. The war crimes charges against him stem from the widespread murder, rape and mutilation that occurred during the bloody civil war in Sierra Leone. It was fought largely by teenagers who were forced to kill, given addictive drugs to provoke violent behavior, and often instructed to rape and plunder.
Taylor is charged with five counts of crimes against humanity, including murder, sexual slavery and violence, and enslavement. He also faces five counts of war crimes, including acts of terrorism and torture, and one count of other serious violations of international humanitarian law.
He has pleaded not guilty to the charges.