A custody battle appears to be looming for Usama bin Laden — if he is captured alive — and who wins could determine whether the world's most wanted terrorist lives or dies.

The United States says it should have jurisdiction in the bin Laden case — and has said it will pursue it. If found guilty of murder in the U.S., bin Laden could get the death penalty.

But Afghanistan's new leader, Hamid Karzai, says bin Laden should be turned over to face international justice if he is found. The chief U.N. war crimes prosecutor agrees. And, if found guilty at a U.N. war crimes tribunal, the most bin Laden could get would be life in prison.

Pierre-Richard Prosper, the U.S. ambassador at large for war crimes, has said the United States believes it has legal power over Sept. 11 crimes.

"As for bin Laden, he is indicted in the United States for his role in the embassy bombings (in Africa) and we would like to see him stand trial for those events in the United States or through a United States process," Prosper said in the Hague, Netherlands.

But in Karzai's vision, the world, not the U.S., would prosecute bin Laden. "A man like that who has committed crimes worldwide must be given to international justice," he said.

The chief U.N. war crimes prosecutor, Carla del Ponte, agreed with Karzai that an international tribunal would be a good idea.

"For so grave a fact, it definitely seems to me to be one of the best possibilities to be able to conduct a process before an international tribunal," she told a news conference organized by Italy's Radical party. She stressed that her comments were her personal opinion and that she had no jurisdiction over Afghanistan.

Karzai Prepares to Take Control

Karzai said his top priorities in office would be to "fight terrorism to the end" and revive Afghanistan's war-wrecked economy.

He also said he envisioned an international peacekeeping force of about 3,000 to 5,000 troops authorized to use force not only in self defense, but to keep the peace until an Afghan defense force can take over.

"If it takes the use of force to keep the peace, why not?" he said. "The basic element is to keep peace."

He said he didn't know where bin Laden or Taliban leader Mullah Mohammed Omar were. But he pledged to hunt down bin Laden and his supporters in their hideouts, so that terrorists wouldn't have "one iota" of a presence left in Afghanistan.

"There's no way we can allow them to stay," Karzai said. "They've killed our people. They have destroyed our land. We will finish them to the end."

The first units of a peacekeeping force, expected to be led by Britain, could be on the ground by Saturday's swearing-in ceremony.

Karzai said the peacekeepers would be welcome to stay "as long as it takes for Afghan stability," but offered no details on what he would like to see them do. He said the creation of an Afghan national army was key to preventing Afghanistan's warlords from undermining security.

Karzai was selected to head Afghanistan's interim administration at U.N.-sponsored talks in Germany earlier this month. Karzai, who was part of the king's delegation, will rule along with a 29-member cabinet for six months.

The king, seen by many as a unifying figure, is to then convene a grand national assembly, or loya jirga, which would choose a government to lead Afghanistan for two years while a constitution is drafted.

Karzai spoke at a news conference in Rome, a day after paying his respects to Afghanistan's former king, Mohammad Zaher Shah, at the exiled monarch's Roman villa and receiving his blessing to be installed on Saturday as the country's interim ruler.

As if to underscore the importance of the moment, Zaher Shah stepped outside the heavily guarded home to make a rare appearance before media. Zaher Shah said he had given Karzai advice on "a lot of things" on how to lead the country, but didn't elaborate.

"He has been giving me advice for many years," said Karzai, a distant relative of the king's and also Pashtun, Afghanistan's dominant ethnic group. "The moment I sat with him, he wished me very, very well and said he was very, very glad that I have taken this charge."

The 87-year-old king, considered the symbolic father of Afghans, presented Karzai with a personal copy of the Quran, encased in a green, leather-bound box.

Karzai kissed the holy book, as well as the king's hands, in thanks.

"This gives me tremendous hope, tremendous hope, that under the guidance of the holy Quran and his majesty's blessings, I'm going back home," Karzai said.

The Associated Press contributed to this report.