KABUL, Afghanistan — Senior Muslim clerics demanded Thursday that an Afghan man on trial for converting from Islam to Christianity be executed, warning that if the government caves in to Western pressure and frees him, they will incite people to "pull him into pieces."

In an unusual move, Secretary of State Condoleezza Rice telephoned President Hamid Karzai on Thursday seeking a "favorable resolution" of the case of Abdul Rahman. The 41-year-old former medical aid worker faces the death penalty under Afghanistan's Islamic laws for becoming a Christian.

His trial has fired passions in this conservative Muslim nation and highlighted a conflict of values between Afghanistan and its Western backers.

"Rejecting Islam is insulting God. We will not allow God to be humiliated. This man must die," said cleric Abdul Raoulf, who is considered a moderate and was jailed three times for opposing the Taliban before the hard-line regime was ousted in 2001.

The trial, which began last week, has caused an international outcry. President Bush has said he is "deeply troubled" by the case and expects the country to "honor the universal principle of freedom."

Rice spokesman Sean McCormack said she told Karzai it is important for the Afghan people to know that freedom of religion is observed in their country. But in deference to the country's sovereignty, Rice evidently did not demand specifically that the trial be halted and the defendant released.

"This is clearly an Afghan decision," McCormack said. "They are a sovereign country."

Still, Rice's direct appeal to a foreign leader in a judicial proceeding in their own country is an unusual move.

German Chancellor Angela Merkel told reporters she had received assurances from Karzai in a telephone call that Rahman would not be sentenced to death.

Diplomats have said the Afghan government is searching for a way to drop the case. On Wednesday, authorities said Rahman is suspected of being mentally ill and would undergo psychological examinations to see whether he is fit to stand trial.

But three Sunni preachers and a Shiite one interviewed by The Associated Press in four of Kabul's most popular mosques said they do not believe Rahman is insane.

"He is not crazy. He went in front of the media and confessed to being a Christian," said Hamidullah, chief cleric at Haji Yacob Mosque.

"The government is scared of the international community. But the people will kill him if he is freed."