Updated

International pressure grew Friday on Afghanistan to free a man on trial for converting from Islam to Christianity, as clerics in Kabul condemned him as an apostate who deserved to die.

Australia's Prime Minister John Howard on Friday joined the chorus of Western leaders to express concern over the case of Abdul Rahman and said he would protest personally to Afghan President Hamid Karzai.

"This is appalling. When I saw the report about this I felt sick literally," Howard told an Australian radio network. "The idea that a person could be punished because of their religious belief and the idea they might be executed is just beyond belief."

Rahman, a 41-year-old former medical aid worker, faces the death penalty under Afghanistan's Islamic laws for becoming a Christian.

Senior clerics in the Afghan capital have voiced strong support for the prosecution and have warned they would incite people to execute Rahman unless he reverted to Islam.

That message was reiterated that at Friday prayers.

Rahman had "committed the greatest sin" by converting to Christianity and deserved to be killed, cleric Abdul Raoulf said in his sermon at Herati Mosque.

"God's way is the right way, and this man whose name is Abdul Rahman is an apostate," he told about 150 worshippers.

Rahman's trial, which started last week, has fired passions in this conservative Muslim nation and highlighted a conflict of values between Afghanistan and its Western backers.

U.S. President George W. Bush expressed alarm this week, and on Thursday, U.S. Secretary of State Condoleezza Rice phoned Karzai, seeking a "favorable resolution" of the case. She said Washington looked forward to that "in the very near future."

The presiding judge in the case and a spokesman for Karzai — who took power after the ouster of the hard-line Taliban regime in a U.S.-led war in late 2001 — declined to comment about the case Friday, the weekly holiday in Afghanistan.

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.

Her direct appeal to a foreign leader in a judicial proceeding in their own country was unusual. 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.

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.