One of the Pope's senior advisers has pulled out of the papal visit to Britain, after reportedly saying the UK is a "Third World country" marked by "a new and aggressive atheism".
Cardinal Walter Kasper, 77, made the remarks in a German magazine interview.
The Vatican said the cardinal had not intended "any kind of slight", and was referring to the UK's multicultural society.
It added that he had simply pulled out of the Pope's visit due to illness.
The German-born cardinal was quoted as saying to the country's Focus magazine that "when you land at Heathrow you think at times you have landed in a Third World country".
He also was reported to have criticised British Airways, saying that when you wear a cross on the airline "you are discriminated against".
Vatican sources said Cardinal Kasper was suffering from gout and had been advised by his doctors not to travel to the UK.
The Pope is spending four days in Scotland and England, starting on Thursday.
The BBC's correspondent in Rome, David Willey, said the cardinal's reported comments were "a slightly clumsy thing to have done on the eve of the visit".
However, he added that he did not think it would have much effect on the Pope's trip to the UK.
Would somebody please inform Her Majesty that she has a great deal of backing if she wanted to "forget" he was coming to visit and spend a relaxing, long weekend in Balmoral. Really, we wouldn't mind, Ma'am!
If you feel benevolent and particularly generous, this writer always appreciates things bought for him from his wishlist