Pope Benedict yesterday tried to dampen the furore over his remarks about Islam, saying he was "deeply sorry" about the anger they had caused.
But there were fears that the violent reaction to his comments would continue as an Italian nun was shot dead in Somalia.
The Vatican said it hoped the "wave of hate" sweeping the world did not lead to "grave consequences" for the church.
Elsewhere there was a mixed reaction to the Pope's attempt to assuage his critics, with some calling off protests but others saying it was not enough.
Benedict said comments that the prophet Mohammed had brought "things only evil and inhuman", which he had quoted in a speech, did not reflect his own view.
The pontiff said he hoped the explanation would "appease hearts" and make clear that he in fact wished for "frank and sincere dialogue". While senior Islamic clerics in India cancelled planned demonstrations yesterday, Muslims in Jordan said the Pope's explanation was not enough.
Mehmet Aydin, a minister overseeing religious affairs in Turkey, which Benedict is due to visit in November, also said it was inadequate.
"You either have to say this `I'm sorry' in a proper way or not say it at all," he said. "Are you sorry for saying such a thing or because of its consequences?"
Officials in strife-torn Somalia said the murder of a nun aged around 60 at the S.O.S. Hospital in Mogadishu may have been linked to the controversy.
"They could be people annoyed by the Pope's speech, which angered all Muslims in the world, or it could have been something to do with S.O.S," said Yusuf Mohamed Siad, head of security for the Islamic courts.
"We will have to clarify this through our investigation."
Witness Mohamud Durguf Derow said: "These gunmen always look for white people to kill, and now the Pope gave them the reason to do their worst."
A Vatican spokesman called the nun's killing "a horrible episode" but hoped it was an "isolated fact".
The Vatican was "following with concern the consequences of this wave of hate, hoping that it does not lead to grave consequences for the church in the world," he told Italian news agency ANSA.
In the West Bank, two churches, neither of them Catholic, were set on fire early yesterday. Protests were held across Iran and a hard-line cleric compared the Pope to US President George Bush saying both were "united in order to repeat the Crusades". A handful of protesters gathered outside London's Westminster Cathedral, chanting slogans and waving placards.
Cardinal Cormac Murphy-O'Connor, leader of the Catholic Church in England and Wales, said the Pope hoped the anger caused by his speech would now subside.
"He sincerely hopes that the regret he has expressed regarding his unintentional disturbance of the sensibility of the Muslim community would be sufficient to allay the intemperate response that was being given," he said. "He has a deep respect for other faiths and other religions and wants a sincere dialogue with them." Fury erupted following the Pope's speech in Germany on Tuesday when he quoted remarks by a 14th Century Byzantine emperor about Islam.
Mohammed Mahdi Akef, leader of the Muslim Brotherhood in Egypt, predicted that anger would soon subside, and relations with Christians should remain "good, civilised and co-operative".
Russian president Vladimir Putin urged world religious leaders to show "responsibility and restraint".